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Group the flow flags under a single struct called flow. The new struct
contains 'stopped' and 'tco_stopped' bools which used to be bits in a
bitfield. The struct also contains the lock protecting them to
potentially share the same cache line.
Note that commit c545b66c6922b (tty: Serialize tcflow() with other tty
flow control changes) added a padding to the original bitfield. It was
for the bitfield to occupy a whole 64b word to avoid interferring stores
on Alpha (cannot we evaporate this arch with weird implications to C
code yet?). But it doesn't work as expected as the padding
(tty_struct::unused) is aligned to a 8B boundary too and occupies some
bytes from the next word.
So make it reliable by:
1) setting __aligned of the struct -- that aligns the start, and
2) making 'unsigned long unused[0]' as the last member of the struct --
pads the end.
This is also the perfect time to start the documentation of tty_struct
where all this lives. So we start by documenting what these bools
actually serve for. And why we do all the alignment dances. Only the few
up-to-date information from the Theodore's comment made it into this new
Kerneldoc comment.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/20210505091928.22010-13-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This loop ends on -1 so the error message will never be printed.
Fixes: 4bcf59a5dea0 ("serial: 8250: 8250_omap: Account for data in flight during DMA teardown")
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YIpd+kOpXKMpEXPf@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This fixes the following checkpatch.pl warnings:
WARNING: Missing a blank line after declarations
WARNING: braces {} are not necessary for any arm of this statement
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/257ffd691b4a062ad017333c9430d69da6dbd29a.1619594713.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Use 'hlist_for_each_entry' instead of hand writing it.
This saves a few lines of code.
The comment about warning generated by some gcc version is also removed.
The way 'hlist_for_each_entry' is written should prevent such a warning to
be emitted.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/14024ddeb2b3a8c5b0138b5ba5083f54d00164a9.1619594713.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The variable id being initialized with a value that is never read
and it is being updated later with a new value. The initialization is
redundant and can be removed. Since id is just being used in a for-loop
inside a local scope, move the declaration of id to that scope.
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Addresses-Coverity: ("Unused value")
Link: https://lore.kernel.org/r/20210426101106.9122-1-colin.king@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Our SoC's have always had a NS16650A UART core and older SoC's would
have a compatible string of: 'compatible = ""ns16550a"' and use the
8250_of driver. Our newer SoC's have added enhancements to the base
core to add support for DMA and accurate high speed baud rates and use
this newer 8250_bcm7271 driver. The Device Tree node for our enhanced
UARTs has a compatible string of: 'compatible = "brcm,bcm7271-uart",
"ns16550a"''. With both drivers running and the link order setup so
that the 8250_bcm7217 driver is initialized before the 8250_of driver,
we should bind the 8250_bcm7271 driver to the enhanced UART, or for
upstream kernels that don't have the 8250_bcm7271 driver, we bind to
the 8250_of driver.
The problem is that when both the 8250_of and 8250_bcm7271 drivers
were running, occasionally the 8250_of driver would be bound to the
enhanced UART instead of the 8250_bcm7271 driver. This was happening
because we use SCMI based clocks which come up late in initialization
and cause probe DEFER's when the two drivers get their clocks.
Occasionally the SCMI clock would become ready between the 8250_bcm7271
probe and the 8250_of probe and the 8250_of driver would be bound. To
fix this we decided to config only our 8250_bcm7271 driver and added
"ns16665a0" to the compatible string so the driver would work on our
older system.
This commit has of_platform_serial_probe() check specifically for the
"brcm,bcm7271-uart" and whether its companion driver is enabled. If it
is the case, and the clock provider is not ready, we want to make sure
that when the 8250_bcm7271.c driver returns EPROBE_DEFER, we are not
getting the UART registered via 8250_of.c.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20210423183206.3917725-1-f.fainelli@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The variable line being initialized with a value that is never read
and it is being updated later with a new value. The initialization is
redundant and can be removed.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Addresses-Coverity: ("Unused value")
Link: https://lore.kernel.org/r/20210423081317.318352-1-colin.king@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Previously this driver's use of devm_ioremap_resource() led to
duplicated calls to __release_region() when unbinding it (one from
serial8250_release_std_resource() and one from devres_release_all()),
the second of which resulted in a warning message:
# echo 1e787000.serial > /sys/bus/platform/drivers/aspeed-vuart/unbind
[33091.774200] Trying to free nonexistent resource <000000001e787000-000000001e78703f>
With this change the driver uses the generic serial8250 code's
UPF_IOREMAP to take care of the register mapping automatically instead
of doing its own devm_ioremap_resource(), thus avoiding the duplicate
__release_region() on unbind.
In doing this we eliminate vuart->regs, since it merely duplicates
vuart->port->port.membase, which we now use for our I/O accesses.
Reported-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210510014231.647-4-zev@bewilderbeest.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Previously this had only been initialized if we hit the throttling path
in aspeed_vuart_handle_irq(); moving it to the probe function is a
slight consistency improvement and avoids redundant reinitialization in
the interrupt handler. It also serves as preparation for converting the
driver's I/O accesses to use port->port.membase instead of its own
vuart->regs.
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210510014231.647-3-zev@bewilderbeest.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This is a small prepatory step for changing the way this driver does
its I/O accesses.
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210510014231.647-2-zev@bewilderbeest.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The value of 'ret' is not used which reported by svace, so just return
instead of break.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Link: https://lore.kernel.org/r/1619484575-26098-1-git-send-email-tiantao6@hisilicon.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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SYSRQ doesn't work with DMA. This is because there is no error
indication whether a symbol had a framing error or not. Actually,
this is not completely correct, there is a bit in the data register
which is set in this case, but we'd have to read change the DMA access
to 16 bit and we'd need to post process the data, thus make the DMA
pointless in the first place.
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-10-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The LPUART can loop the RX and TX signal. Add support for it.
Please note, this was only tested on the 32 bit version of the LPUART.
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-9-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The LPUART doesn't have the ability to control the RTS or CTS line
manually. Instead it will set it automatically when data is send or
handle it when data is received. Thus drop the wrong code in set_mctrl.
For the 32 bit version this was already done in the commit 2b30efe2e88a
("tty: serial: lpuart: Remove unnecessary code from set_mctrl"). Keep
the 8-bit version in sync and remove it there, too.
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-8-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The wrong code in set_mctrl() was already removed in commit 2b30efe2e88a
("tty: serial: lpuart: Remove unnecessary code from set_mctrl"), but the
code in get_mctrl() wasn't removed. It will not return the state of the
RTS or CTS line but whether automatic flow control is enabled, which is
wrong for the get_mctrl(). Thus remove it.
Fixes: 2b30efe2e88a ("tty: serial: lpuart: Remove unnecessary code from set_mctrl")
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-7-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Although there is already sysrq characters handling, a break condition
was never detected. Add support for it.
The LPUART can't distinguish between a framing error and a break
condition. We assume it is a break if the received data is all zero.
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-6-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Instead of uart_handle_sysrq_char() use uart_prepare_sysrq_char() and
uart_unlock_and_check_sysrq(). This will call handle_sysrq() without
holding the port lock, which in turn let us drop the spin_trylock hack.
Suggested-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-5-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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>From commit 75f4e830fa9c ("serial: do not restore interrupt state in
sysrq helper"):
Since commit 81e2073c175b ("genirq: Disable interrupts for force
threaded handlers") interrupt handlers that are not explicitly
requested as threaded are always called with interrupts disabled and
there is no need to save the interrupt state when taking the port
lock.
Apply this also to fsl_lpuart in prepartion for sysrq handling with
uart_unlock_and_check_sysrq().
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-4-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Use the corresponding macro instead of the magic number. While at it,
drop the useless cast to "unsigned char".
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-3-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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lpuart_rx_dma_startup() is used for both the 8 bit and the 32 bit
version of the LPUART. Modify the UARTCR only for the 8 bit version.
Fixes: f4eef224a09f ("serial: fsl_lpuart: add sysrq support when using dma")
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-2-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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We should be very careful about the register values that will be used
for division or modulo operations, althrough the possibility that the
UARTBAUD register value is zero is very low, but we had better to deal
with the "bad data" of hardware in advance to avoid division or modulo
by zero leading to undefined kernel behavior.
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20210427021226.27468-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Pull power management updates from Rafael Wysocki:
"These add some new hardware support (for example, IceLake-D idle
states in intel_idle), fix some issues (for example, the handling of
negative "sleep length" values in cpuidle governors), add new
functionality to the existing drivers (for example, scale-invariance
support in the ACPI CPPC cpufreq driver) and clean up code all over.
Specifics:
- Add idle states table for IceLake-D to the intel_idle driver and
update IceLake-X C6 data in it (Artem Bityutskiy).
- Fix the C7 idle state on Tegra114 in the tegra cpuidle driver and
drop the unused do_idle() firmware call from it (Dmitry Osipenko).
- Fix cpuidle-qcom-spm Kconfig entry (He Ying).
- Fix handling of possible negative tick_nohz_get_next_hrtimer()
return values of in cpuidle governors (Rafael Wysocki).
- Add support for frequency-invariance to the ACPI CPPC cpufreq
driver and update the frequency-invariance engine (FIE) to use it
as needed (Viresh Kumar).
- Simplify the default delay_us setting in the ACPI CPPC cpufreq
driver (Tom Saeger).
- Clean up frequency-related computations in the intel_pstate cpufreq
driver (Rafael Wysocki).
- Fix TBG parent setting for load levels in the armada-37xx cpufreq
driver and drop the CPU PM clock .set_parent method for armada-37xx
(Marek Behún).
- Fix multiple issues in the armada-37xx cpufreq driver (Pali Rohár).
- Fix handling of dev_pm_opp_of_cpumask_add_table() return values in
cpufreq-dt to take the -EPROBE_DEFER one into acconut as
appropriate (Quanyang Wang).
- Fix format string in ia64-acpi-cpufreq (Sergei Trofimovich).
- Drop the unused for_each_policy() macro from cpufreq (Shaokun
Zhang).
- Simplify computations in the schedutil cpufreq governor to avoid
unnecessary overhead (Yue Hu).
- Fix typos in the s5pv210 cpufreq driver (Bhaskar Chowdhury).
- Fix cpufreq documentation links in Kconfig (Alexander Monakov).
- Fix PCI device power state handling in pci_enable_device_flags() to
avoid issuse in some cases when the device depends on an ACPI power
resource (Rafael Wysocki).
- Add missing documentation of pm_runtime_resume_and_get() (Alan
Stern).
- Add missing static inline stub for pm_runtime_has_no_callbacks() to
pm_runtime.h and drop the unused try_to_freeze_nowarn() definition
(YueHaibing).
- Drop duplicate struct device declaration from pm.h and fix a
structure type declaration in intel_rapl.h (Wan Jiabing).
- Use dev_set_name() instead of an open-coded equivalent of it in the
wakeup sources code and drop a redundant local variable
initialization from it (Andy Shevchenko, Colin Ian King).
- Use crc32 instead of md5 for e820 memory map integrity check during
resume from hibernation on x86 (Chris von Recklinghausen).
- Fix typos in comments in the system-wide and hibernation support
code (Lu Jialin).
- Modify the generic power domains (genpd) code to avoid resuming
devices in the "prepare" phase of system-wide suspend and
hibernation (Ulf Hansson).
- Add Hygon Fam18h RAPL support to the intel_rapl power capping
driver (Pu Wen).
- Add MAINTAINERS entry for the dynamic thermal power management
(DTPM) code (Daniel Lezcano).
- Add devm variants of operating performance points (OPP) API
functions and switch over some users of the OPP framework to the
new resource-managed API (Yangtao Li and Dmitry Osipenko).
- Update devfreq core:
* Register devfreq devices as cooling devices on demand (Daniel
Lezcano).
* Add missing unlock opeation in devfreq_add_device() (Lukasz
Luba).
* Use the next frequency as resume_freq instead of the previous
frequency when using the opp-suspend property (Dong Aisheng).
* Check get_dev_status in devfreq_update_stats() (Dong Aisheng).
* Fix set_freq path for the userspace governor in Kconfig (Dong
Aisheng).
* Remove invalid description of get_target_freq() (Dong Aisheng).
- Update devfreq drivers:
* imx8m-ddrc: Remove imx8m_ddrc_get_dev_status() and unneeded
of_match_ptr() (Dong Aisheng, Fabio Estevam).
* rk3399_dmc: dt-bindings: Add rockchip,pmu phandle and drop
references to undefined symbols (Enric Balletbo i Serra, Gaël
PORTAY).
* rk3399_dmc: Use dev_err_probe() to simplify the code (Krzysztof
Kozlowski).
* imx-bus: Remove unneeded of_match_ptr() (Fabio Estevam).
- Fix kernel-doc warnings in three places (Pierre-Louis Bossart).
- Fix typo in the pm-graph utility code (Ricardo Ribalda)"
* tag 'pm-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (74 commits)
PM: wakeup: remove redundant assignment to variable retval
PM: hibernate: x86: Use crc32 instead of md5 for hibernation e820 integrity check
cpufreq: Kconfig: fix documentation links
PM: wakeup: use dev_set_name() directly
PM: runtime: Add documentation for pm_runtime_resume_and_get()
cpufreq: intel_pstate: Simplify intel_pstate_update_perf_limits()
cpufreq: armada-37xx: Fix module unloading
cpufreq: armada-37xx: Remove cur_frequency variable
cpufreq: armada-37xx: Fix determining base CPU frequency
cpufreq: armada-37xx: Fix driver cleanup when registration failed
clk: mvebu: armada-37xx-periph: Fix workaround for switching from L1 to L0
clk: mvebu: armada-37xx-periph: Fix switching CPU freq from 250 Mhz to 1 GHz
cpufreq: armada-37xx: Fix the AVS value for load L1
clk: mvebu: armada-37xx-periph: remove .set_parent method for CPU PM clock
cpufreq: armada-37xx: Fix setting TBG parent for load levels
cpuidle: Fix ARM_QCOM_SPM_CPUIDLE configuration
cpuidle: tegra: Remove do_idle firmware call
cpuidle: tegra: Fix C7 idling state on Tegra114
PM: sleep: fix typos in comments
cpufreq: Remove unused for_each_policy macro
...
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Pull ARM SoC driver updates from Arnd Bergmann:
"Updates for SoC specific drivers include a few subsystems that have
their own maintainers but send them through the soc tree:
TEE/OP-TEE:
- Add tracepoints around calls to secure world
Memory controller drivers:
- Minor fixes for Renesas, Exynos, Mediatek and Tegra platforms
- Add debug statistics to Tegra20 memory controller
- Update Tegra bindings and convert to dtschema
ARM SCMI Firmware:
- Support for modular SCMI protocols and vendor specific extensions
- New SCMI IIO driver
- Per-cpu DVFS
The other driver changes are all from the platform maintainers
directly and reflect the drivers that don't fit into any other
subsystem as well as treewide changes for a particular platform.
SoCFPGA:
- Various cleanups contributed by Krzysztof Kozlowski
Mediatek:
- add MT8183 support to mutex driver
- MMSYS: use per SoC array to describe the possible routing
- add MMSYS support for MT8183 and MT8167
- add support for PMIC wrapper with integrated arbiter
- add support for MT8192/MT6873
Tegra:
- Bug fixes to PMC and clock drivers
NXP/i.MX:
- Update SCU power domain driver to keep console domain power on.
- Add missing ADC1 power domain to SCU power domain driver.
- Update comments for single global power domain in SCU power domain
driver.
- Add i.MX51/i.MX53 unique id support to i.MX SoC driver.
NXP/FSL SoC driver updates for v5.13
- Add ACPI support for RCPM driver
- Use generic io{read,write} for QE drivers after performance
optimized for PowerPC
- Fix QBMAN probe to cleanup HW states correctly for kexec
- Various cleanup and style fix for QBMAN/QE/GUTS drivers
OMAP:
- Preparation to use devicetree for genpd
- ti-sysc needs iorange check improved when the interconnect target
module has no control registers listed
- ti-sysc needs to probe l4_wkup and l4_cfg interconnects first to
avoid issues with missing resources and unnecessary deferred probe
- ti-sysc debug option can now detect more devices
- ti-sysc now warns if an old incomplete devicetree data is found as
we now rely on it being complete for am3 and 4
- soc init code needs to check for prcm and prm nodes for omap4/5 and
dra7
- omap-prm driver needs to enable autoidle retention support for
omap4
- omap5 clocks are missing gpmc and ocmc clock registers
- pci-dra7xx now needs to use builtin_platform_driver instead of
using builtin_platform_driver_probe for deferred probe to work
Raspberry Pi:
- Fix-up all RPi firmware drivers so as for unbind to happen in an
orderly fashion
- Support for RPi's PoE hat PWM bus
Qualcomm
- Improved detection for SCM calling conventions
- Support for OEM specific wifi firmware path
- Added drivers for SC7280/SM8350: RPMH, LLCC< AOSS QMP"
* tag 'arm-drivers-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (165 commits)
soc: aspeed: fix a ternary sign expansion bug
memory: mtk-smi: Add device-link between smi-larb and smi-common
memory: samsung: exynos5422-dmc: handle clk_set_parent() failure
memory: renesas-rpc-if: fix possible NULL pointer dereference of resource
clk: socfpga: fix iomem pointer cast on 64-bit
soc: aspeed: Adapt to new LPC device tree layout
pinctrl: aspeed-g5: Adapt to new LPC device tree layout
ipmi: kcs: aspeed: Adapt to new LPC DTS layout
ARM: dts: Remove LPC BMC and Host partitions
dt-bindings: aspeed-lpc: Remove LPC partitioning
soc: fsl: enable acpi support in RCPM driver
soc: qcom: mdt_loader: Detect truncated read of segments
soc: qcom: mdt_loader: Validate that p_filesz < p_memsz
soc: qcom: pdr: Fix error return code in pdr_register_listener
firmware: qcom_scm: Fix kernel-doc function names to match
firmware: qcom_scm: Suppress sysfs bind attributes
firmware: qcom_scm: Workaround lack of "is available" call on SC7180
firmware: qcom_scm: Reduce locking section for __get_convention()
firmware: qcom_scm: Make __qcom_scm_is_call_available() return bool
Revert "soc: fsl: qe: introduce qe_io{read,write}* wrappers"
...
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Allow more drivers to be compile tested more easily, for example, when
doing subsystem-wide changes.
Verified on X86_64 as well as arm, powerpc and m68k with minimal configs
in order to catch missing implicit build dependencies (e.g. MAILBOX for
SERIAL_TEGRA_TCU).
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210422080211.29326-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add the support for two optional DT properties, to configure RX and TX
FIFO thresholds:
- rx-threshold
- tx-threshold
This replaces hard-coded 8 bytes threshold. Keep 8 as the default value if
not specified, for backward compatibility.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>
Changes in v2:
Change added properties naming as proposed by Rob Herring.
Link: https://lore.kernel.org/r/20210413174015.23011-5-erwan.leray@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit c8dbdc842d30 ("serial: xuartps: Rewrite the interrupt handling
logic") reworked the driver interrupt processing but also, without
comment, added an unnecessary workaround for the infamous low_latency
behaviour of tty_flip_buffer_push() which had been removed years
before.
Specifically, since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Cc: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-27-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit de49df58366f ("tty: serial: vt8500: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Cc: Tony Prisk <linux@prisktech.co.nz>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-26-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The timbuart driver has always carried a workaround for the infamous
low_latency behaviour of tty_flip_buffer_push() which required not
holding the port lock when the low_latency flag was set.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-25-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The sunsu driver has been carrying a workaround for the infamous
low_latency behaviour of tty_flip_buffer_push() by dropping and
reacquiring the port lock in the interrupt handler since 2004.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Cc: "David S. Miller" <davem@davemloft.net>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-24-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The sifive driver has always carried an unnecessary workaround for the
infamous low_latency behaviour of tty_flip_buffer_push() which had been
removed years before the driver was added by commit 45c054d0815b ("tty:
serial: add driver for the SiFive UART").
Specifically, since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-23-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit f5ee56cc184e ("[PATCH] txx9 serial update") worked around the
infamous low_latency behaviour of tty_flip_buffer_push() by simply
dropping and reacquiring the port lock in the interrupt handler.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-22-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit 53e0e6706c76 ("tty: serial: sa1100: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-21-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit de7053c77123 ("tty: serial: rp2: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Cc: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-20-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The rda driver has always carried an unnecessary workaround for the
infamous low_latency behaviour of tty_flip_buffer_push(), which had
been removed years before the driver was added by commit c10b13325ced
("tty: serial: Add RDA8810PL UART driver").
Specifically, since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-19-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The owl driver has always carried an unnecessary workaround for the
infamous low_latency behaviour of tty_flip_buffer_push(), which had
been removed years before the driver was added by commit fc60a8b675bd
("tty: serial: owl: Implement console driver").
Specifically, since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-18-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit f77232dab25b ("tty: serial: msm: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-17-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit fbe543b412ce ("Fix a potential issue in mpc52xx uart driver")
worked around the infamous low_latency behaviour of
tty_flip_buffer_push() by simply dropping and reacquiring the port lock
in the interrupt handler.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-16-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The meson driver has always carried an unnecessary workaround for the
infamous low_latency behaviour of tty_flip_buffer_push(), which had
already been removed by the time the driver was added by commit
ff7693d079e5 ("ARM: meson: serial: add MesonX SoC on-chip uart driver").
Specifically, since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-15-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit 5275ad70fed3 ("tty: serial: mcf: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-14-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit ec128510905c ("tty: serial: lpc32xx_hs: drop uart_port->lock
before calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-13-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit 5faf75d7fed2 ("tty: serial: icom: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-12-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit b4d499241c34 ("tty: serial: bcm63xx: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-11-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit 1ecc26bd2789 ("atmel_serial: split the interrupt handler") worked
around the infamous low_latency behaviour of tty_flip_buffer_push() by
dropping and reacquiring the port lock in the tasklet callback.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Cc: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-10-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit 3fa1200851c7 ("tty: serial: arc: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-9-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit b16c8e3eed12 ("tty: serial: ar933x: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-8-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit 78d34d75c84d ("tty: serial: apbuart: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-7-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit ead76f329f77 ("ARM: 6763/1: pl011: add optional RX DMA to PL011
v2") added RX DMA support and also reproduced the workaround for the
infamous low_latency behaviour of tty_flip_buffer_push() by dropping and
reacquiring the port lock during receive processing.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Note that the port lock is also dropped in the PIO path
(see pl011_rx_chars), but it is not clear whether this is still needed
by the DMA code added by the aforementioned commit.
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Russell King <linux@armlinux.org.uk>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-6-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit 2389b272168c ("[ARM] 4417/1: Serial: Fix AMBA drivers locking")
worked around the infamous low_latency behaviour of
tty_flip_buffer_push() by simply dropping and reacquiring the port lock
in the interrupt handler.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-5-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit dd085ed8ef6c ("tty: serial: altera: drop uart_port->lock before
calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Cc: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit 53dd0ba7a6f4 ("tty: serial: altera_jtag: drop uart_port->lock
before calling tty_flip_buffer_push()") claimed to address a locking
issue but only provided a dubious lockdep splat from an unrelated
driver, which in the end turned out to be due a broken local change
carried by the author.
Unfortunately these patches were merged before the issue had been
analysed properly so the commit messages makes no sense whatsoever.
The real issue was first seen on RT which at the time effectively always
set the low_latency flag for all serial drivers by patching
tty_flip_buffer_push(). This in turn revealed that many drivers did not
handle the infamous low_latency behaviour which meant that data was
pushed immediately to the line discipline instead of being deferred to a
work queue.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks
around.
Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
Cc: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Jiri Slaby
Dan Carpenter
Christophe JAILLET
Colin Ian King
Jim Quinlan
Zev Weiss
Tian Tao
Michael Walle
Sherry Sun
Linus Torvalds
Johan Hovold
Fabrice Gasnier