<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-dev/arch/powerpc/kernel/eeh.c, branch linus/master</title>
<subtitle>Linux kernel development work - see feature branches</subtitle>
<id>https://git.zx2c4.com/linux-dev/atom/arch/powerpc/kernel/eeh.c?h=linus%2Fmaster</id>
<link rel='self' href='https://git.zx2c4.com/linux-dev/atom/arch/powerpc/kernel/eeh.c?h=linus%2Fmaster'/>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/'/>
<updated>2022-05-05T12:12:44Z</updated>
<entry>
<title>powerpc: fix typos in comments</title>
<updated>2022-05-05T12:12:44Z</updated>
<author>
<name>Julia Lawall</name>
<email>Julia.Lawall@inria.fr</email>
</author>
<published>2022-04-30T18:56:54Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=1fd02f6605b855b4af2883f29a2abc88bdf17857'/>
<id>urn:sha1:1fd02f6605b855b4af2883f29a2abc88bdf17857</id>
<content type='text'>
Various spelling mistakes in comments.
Detected with the help of Coccinelle.

Signed-off-by: Julia Lawall &lt;Julia.Lawall@inria.fr&gt;
Reviewed-by: Joel Stanley &lt;joel@jms.id.au&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20220430185654.5855-1-Julia.Lawall@inria.fr

</content>
</entry>
<entry>
<title>Merge tag 'pci-v5.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci</title>
<updated>2021-11-06T21:36:12Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-11-06T21:36:12Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=0c5c62ddf88c34bc83b66e4ac9beb2bb0e1887d4'/>
<id>urn:sha1:0c5c62ddf88c34bc83b66e4ac9beb2bb0e1887d4</id>
<content type='text'>
Pull pci updates from Bjorn Helgaas:
 "Enumeration:
   - Conserve IRQs by setting up portdrv IRQs only when there are users
     (Jan Kiszka)
   - Rework and simplify _OSC negotiation for control of PCIe features
     (Joerg Roedel)
   - Remove struct pci_dev.driver pointer since it's redundant with the
     struct device.driver pointer (Uwe Kleine-König)

  Resource management:
   - Coalesce contiguous host bridge apertures from _CRS to accommodate
     BARs that cover more than one aperture (Kai-Heng Feng)

  Sysfs:
   - Check CAP_SYS_ADMIN before parsing user input (Krzysztof
     Wilczyński)
   - Return -EINVAL consistently from "store" functions (Krzysztof
     Wilczyński)
   - Use sysfs_emit() in endpoint "show" functions to avoid buffer
     overruns (Kunihiko Hayashi)

  PCIe native device hotplug:
   - Ignore Link Down/Up caused by resets during error recovery so
     endpoint drivers can remain bound to the device (Lukas Wunner)

  Virtualization:
   - Avoid bus resets on Atheros QCA6174, where they hang the device
     (Ingmar Klein)
   - Work around Pericom PI7C9X2G switch packet drop erratum by using
     store and forward mode instead of cut-through (Nathan Rossi)
   - Avoid trying to enable AtomicOps on VFs; the PF setting applies to
     all VFs (Selvin Xavier)

  MSI:
   - Document that /sys/bus/pci/devices/.../irq contains the legacy INTx
     interrupt or the IRQ of the first MSI (not MSI-X) vector (Barry
     Song)

  VPD:
   - Add pci_read_vpd_any() and pci_write_vpd_any() to access anywhere
     in the possible VPD space; use these to simplify the cxgb3 driver
     (Heiner Kallweit)

  Peer-to-peer DMA:
   - Add (not subtract) the bus offset when calculating DMA address
     (Wang Lu)

  ASPM:
   - Re-enable LTR at Downstream Ports so they don't report Unsupported
     Requests when reset or hot-added devices send LTR messages
     (Mingchuang Qiao)

  Apple PCIe controller driver:
   - Add driver for Apple M1 PCIe controller (Alyssa Rosenzweig, Marc
     Zyngier)

  Cadence PCIe controller driver:
   - Return success when probe succeeds instead of falling into error
     path (Li Chen)

  HiSilicon Kirin PCIe controller driver:
   - Reorganize PHY logic and add support for external PHY drivers
     (Mauro Carvalho Chehab)
   - Support PERST# GPIOs for HiKey970 external PEX 8606 bridge (Mauro
     Carvalho Chehab)
   - Add Kirin 970 support (Mauro Carvalho Chehab)
   - Make driver removable (Mauro Carvalho Chehab)

  Intel VMD host bridge driver:
   - If IOMMU supports interrupt remapping, leave VMD MSI-X remapping
     enabled (Adrian Huang)
   - Number each controller so we can tell them apart in
     /proc/interrupts (Chunguang Xu)
   - Avoid building on UML because VMD depends on x86 bare metal APIs
     (Johannes Berg)

  Marvell Aardvark PCIe controller driver:
   - Define macros for PCI_EXP_DEVCTL_PAYLOAD_* (Pali Rohár)
   - Set Max Payload Size to 512 bytes per Marvell spec (Pali Rohár)
   - Downgrade PIO Response Status messages to debug level (Marek Behún)
   - Preserve CRS SV (Config Request Retry Software Visibility) bit in
     emulated Root Control register (Pali Rohár)
   - Fix issue in configuring reference clock (Pali Rohár)
   - Don't clear status bits for masked interrupts (Pali Rohár)
   - Don't mask unused interrupts (Pali Rohár)
   - Avoid code repetition in advk_pcie_rd_conf() (Marek Behún)
   - Retry config accesses on CRS response (Pali Rohár)
   - Simplify emulated Root Capabilities initialization (Pali Rohár)
   - Fix several link training issues (Pali Rohár)
   - Fix link-up checking via LTSSM (Pali Rohár)
   - Fix reporting of Data Link Layer Link Active (Pali Rohár)
   - Fix emulation of W1C bits (Marek Behún)
   - Fix MSI domain .alloc() method to return zero on success (Marek
     Behún)
   - Read entire 16-bit MSI vector in MSI handler, not just low 8 bits
     (Marek Behún)
   - Clear Root Port I/O Space, Memory Space, and Bus Master Enable bits
     at startup; PCI core will set those as necessary (Pali Rohár)
   - When operating as a Root Port, set class code to "PCI Bridge"
     instead of the default "Mass Storage Controller" (Pali Rohár)
   - Add emulation for PCI_BRIDGE_CTL_BUS_RESET since aardvark doesn't
     implement this per spec (Pali Rohár)
   - Add emulation of option ROM BAR since aardvark doesn't implement
     this per spec (Pali Rohár)

  MediaTek MT7621 PCIe controller driver:
   - Add MediaTek MT7621 PCIe host controller driver and DT binding
     (Sergio Paracuellos)

  Qualcomm PCIe controller driver:
   - Add SC8180x compatible string (Bjorn Andersson)
   - Add endpoint controller driver and DT binding (Manivannan
     Sadhasivam)
   - Restructure to use of_device_get_match_data() (Prasad Malisetty)
   - Add SC7280-specific pcie_1_pipe_clk_src handling (Prasad Malisetty)

  Renesas R-Car PCIe controller driver:
   - Remove unnecessary includes (Geert Uytterhoeven)

  Rockchip DesignWare PCIe controller driver:
   - Add DT binding (Simon Xue)

  Socionext UniPhier Pro5 controller driver:
   - Serialize INTx masking/unmasking (Kunihiko Hayashi)

  Synopsys DesignWare PCIe controller driver:
   - Run dwc .host_init() method before registering MSI interrupt
     handler so we can deal with pending interrupts left by bootloader
     (Bjorn Andersson)
   - Clean up Kconfig dependencies (Andy Shevchenko)
   - Export symbols to allow more modular drivers (Luca Ceresoli)

  TI DRA7xx PCIe controller driver:
   - Allow host and endpoint drivers to be modules (Luca Ceresoli)
   - Enable external clock if present (Luca Ceresoli)

  TI J721E PCIe driver:
   - Disable PHY when probe fails after initializing it (Christophe
     JAILLET)

  MicroSemi Switchtec management driver:
   - Return error to application when command execution fails because an
     out-of-band reset has cleared the device BARs, Memory Space Enable,
     etc (Kelvin Cao)
   - Fix MRPC error status handling issue (Kelvin Cao)
   - Mask out other bits when reading of management VEP instance ID
     (Kelvin Cao)
   - Return EOPNOTSUPP instead of ENOTSUPP from sysfs show functions
     (Kelvin Cao)
   - Add check of event support (Logan Gunthorpe)

  Miscellaneous:
   - Remove unused pci_pool wrappers, which have been replaced by
     dma_pool (Cai Huoqing)
   - Use 'unsigned int' instead of bare 'unsigned' (Krzysztof
     Wilczyński)
   - Use kstrtobool() directly, sans strtobool() wrapper (Krzysztof
     Wilczyński)
   - Fix some sscanf(), sprintf() format mismatches (Krzysztof
     Wilczyński)
   - Update PCI subsystem information in MAINTAINERS (Krzysztof
     Wilczyński)
   - Correct some misspellings (Krzysztof Wilczyński)"

* tag 'pci-v5.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (137 commits)
  PCI: Add ACS quirk for Pericom PI7C9X2G switches
  PCI: apple: Configure RID to SID mapper on device addition
  iommu/dart: Exclude MSI doorbell from PCIe device IOVA range
  PCI: apple: Implement MSI support
  PCI: apple: Add INTx and per-port interrupt support
  PCI: kirin: Allow removing the driver
  PCI: kirin: De-init the dwc driver
  PCI: kirin: Disable clkreq during poweroff sequence
  PCI: kirin: Move the power-off code to a common routine
  PCI: kirin: Add power_off support for Kirin 960 PHY
  PCI: kirin: Allow building it as a module
  PCI: kirin: Add MODULE_* macros
  PCI: kirin: Add Kirin 970 compatible
  PCI: kirin: Support PERST# GPIOs for HiKey970 external PEX 8606 bridge
  PCI: apple: Set up reference clocks when probing
  PCI: apple: Add initial hardware bring-up
  PCI: of: Allow matching of an interrupt-map local to a PCI device
  of/irq: Allow matching of an interrupt-map local to an interrupt controller
  irqdomain: Make of_phandle_args_to_fwspec() generally available
  PCI: Do not enable AtomicOps on VFs
  ...
</content>
</entry>
<entry>
<title>powerpc/eeh: Fix docstrings in eeh.c</title>
<updated>2021-10-13T05:45:33Z</updated>
<author>
<name>Kai Song</name>
<email>songkai01@inspur.com</email>
</author>
<published>2021-10-09T04:16:30Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=b616230e2325e5560330c40172a4d4e4c5da2c59'/>
<id>urn:sha1:b616230e2325e5560330c40172a4d4e4c5da2c59</id>
<content type='text'>
We fix the following warnings when building kernel with W=1:
arch/powerpc/kernel/eeh.c:598: warning: Function parameter or member 'function' not described in 'eeh_pci_enable'
arch/powerpc/kernel/eeh.c:774: warning: Function parameter or member 'edev' not described in 'eeh_set_dev_freset'
arch/powerpc/kernel/eeh.c:774: warning: expecting prototype for eeh_set_pe_freset(). Prototype was for eeh_set_dev_freset() instead
arch/powerpc/kernel/eeh.c:814: warning: Function parameter or member 'include_passed' not described in 'eeh_pe_reset_full'
arch/powerpc/kernel/eeh.c:944: warning: Function parameter or member 'ops' not described in 'eeh_init'
arch/powerpc/kernel/eeh.c:1451: warning: Function parameter or member 'include_passed' not described in 'eeh_pe_reset'
arch/powerpc/kernel/eeh.c:1526: warning: Function parameter or member 'func' not described in 'eeh_pe_inject_err'
arch/powerpc/kernel/eeh.c:1526: warning: Excess function parameter 'function' described in 'eeh_pe_inject_err'

Signed-off-by: Kai Song &lt;songkai01@inspur.com&gt;
Reviewed-by: Daniel Axtens &lt;dja@axtens.net&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20211009041630.4135-1-songkai01@inspur.com

</content>
</entry>
<entry>
<title>powerpc/eeh: Use dev_driver_string() instead of struct pci_dev-&gt;driver-&gt;name</title>
<updated>2021-10-12T22:50:12Z</updated>
<author>
<name>Uwe Kleine-König</name>
<email>u.kleine-koenig@pengutronix.de</email>
</author>
<published>2021-10-04T12:59:29Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=5a72431ec318ed38b02a413b1e4ab934e5d3451e'/>
<id>urn:sha1:5a72431ec318ed38b02a413b1e4ab934e5d3451e</id>
<content type='text'>
Replace pdev-&gt;driver-&gt;name by dev_driver_string() for the corresponding
struct device.  This is a step toward removing pci_dev-&gt;driver.

Move the function nearer its only user and instead of the ?: operator use a
normal "if" which is more readable.

Link: https://lore.kernel.org/r/20211004125935.2300113-6-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König &lt;u.kleine-koenig@pengutronix.de&gt;
Signed-off-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
</content>
</entry>
<entry>
<title>powerpc: rename powerpc_debugfs_root to arch_debugfs_dir</title>
<updated>2021-08-13T12:04:26Z</updated>
<author>
<name>Aneesh Kumar K.V</name>
<email>aneesh.kumar@linux.ibm.com</email>
</author>
<published>2021-08-12T13:28:31Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=dbf77fed8b302e87561c7c2fc06050c88f4d3120'/>
<id>urn:sha1:dbf77fed8b302e87561c7c2fc06050c88f4d3120</id>
<content type='text'>
No functional change in this patch. arch_debugfs_dir is the generic kernel
name declared in linux/debugfs.h for arch-specific debugfs directory.
Architectures like x86/s390 already use the name. Rename powerpc
specific powerpc_debugfs_root to arch_debugfs_dir.

Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20210812132831.233794-2-aneesh.kumar@linux.ibm.com

</content>
</entry>
<entry>
<title>powerpc: Fix reverse map real-mode address lookup with huge vmalloc</title>
<updated>2021-05-28T12:54:27Z</updated>
<author>
<name>Nicholas Piggin</name>
<email>npiggin@gmail.com</email>
</author>
<published>2021-05-26T12:00:05Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=5362a4b6ee6136018558ef6b2c4701aa15ebc602'/>
<id>urn:sha1:5362a4b6ee6136018558ef6b2c4701aa15ebc602</id>
<content type='text'>
real_vmalloc_addr() does not currently work for huge vmalloc, which is
what the reverse map can be allocated with for radix host, hash guest.

Extract the hugepage aware equivalent from eeh code into a helper, and
convert existing sites including this one to use it.

Fixes: 8abddd968a30 ("powerpc/64s/radix: Enable huge vmalloc mappings")
Signed-off-by: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20210526120005.3432222-1-npiggin@gmail.com
</content>
</entry>
<entry>
<title>powerpc/eeh: remove unneeded semicolon</title>
<updated>2021-04-22T15:38:04Z</updated>
<author>
<name>Yang Li</name>
<email>yang.lee@linux.alibaba.com</email>
</author>
<published>2021-02-02T03:21:36Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=f3d03fc748d4e48f4cd8dea1bfeb173cb3b0c19f'/>
<id>urn:sha1:f3d03fc748d4e48f4cd8dea1bfeb173cb3b0c19f</id>
<content type='text'>
Eliminate the following coccicheck warning:
./arch/powerpc/kernel/eeh.c:782:2-3: Unneeded semicolon

Reported-by: Abaci Robot &lt;abaci@linux.alibaba.com&gt;
Signed-off-by: Yang Li &lt;yang.lee@linux.alibaba.com&gt;
Reviewed-by: Oliver O'Halloran &lt;oohall@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/1612236096-91154-1-git-send-email-yang.lee@linux.alibaba.com

</content>
</entry>
<entry>
<title>powerpc/eeh: Fix EEH handling for hugepages in ioremap space.</title>
<updated>2021-04-14T13:04:15Z</updated>
<author>
<name>Mahesh Salgaonkar</name>
<email>mahesh@linux.ibm.com</email>
</author>
<published>2021-04-12T07:52:50Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=5ae5bc12d0728db60a0aa9b62160ffc038875f1a'/>
<id>urn:sha1:5ae5bc12d0728db60a0aa9b62160ffc038875f1a</id>
<content type='text'>
During the EEH MMIO error checking, the current implementation fails to map
the (virtual) MMIO address back to the pci device on radix with hugepage
mappings for I/O. This results into failure to dispatch EEH event with no
recovery even when EEH capability has been enabled on the device.

eeh_check_failure(token)		# token = virtual MMIO address
  addr = eeh_token_to_phys(token);
  edev = eeh_addr_cache_get_dev(addr);
  if (!edev)
	return 0;
  eeh_dev_check_failure(edev);	&lt;= Dispatch the EEH event

In case of hugepage mappings, eeh_token_to_phys() has a bug in virt -&gt; phys
translation that results in wrong physical address, which is then passed to
eeh_addr_cache_get_dev() to match it against cached pci I/O address ranges
to get to a PCI device. Hence, it fails to find a match and the EEH event
never gets dispatched leaving the device in failed state.

The commit 33439620680be ("powerpc/eeh: Handle hugepages in ioremap space")
introduced following logic to translate virt to phys for hugepage mappings:

eeh_token_to_phys():
+	pa = pte_pfn(*ptep);
+
+	/* On radix we can do hugepage mappings for io, so handle that */
+       if (hugepage_shift) {
+               pa &lt;&lt;= hugepage_shift;			&lt;= This is wrong
+               pa |= token &amp; ((1ul &lt;&lt; hugepage_shift) - 1);
+       }

This patch fixes the virt -&gt; phys translation in eeh_token_to_phys()
function.

  $ cat /sys/kernel/debug/powerpc/eeh_address_cache
  mem addr range [0x0000040080000000-0x00000400807fffff]: 0030:01:00.1
  mem addr range [0x0000040080800000-0x0000040080ffffff]: 0030:01:00.1
  mem addr range [0x0000040081000000-0x00000400817fffff]: 0030:01:00.0
  mem addr range [0x0000040081800000-0x0000040081ffffff]: 0030:01:00.0
  mem addr range [0x0000040082000000-0x000004008207ffff]: 0030:01:00.1
  mem addr range [0x0000040082080000-0x00000400820fffff]: 0030:01:00.0
  mem addr range [0x0000040082100000-0x000004008210ffff]: 0030:01:00.1
  mem addr range [0x0000040082110000-0x000004008211ffff]: 0030:01:00.0

Above is the list of cached io address ranges of pci 0030:01:00.&lt;fn&gt;.

Before this patch:

Tracing 'arg1' of function eeh_addr_cache_get_dev() during error injection
clearly shows that 'addr=' contains wrong physical address:

   kworker/u16:0-7       [001] ....   108.883775: eeh_addr_cache_get_dev:
	   (eeh_addr_cache_get_dev+0xc/0xf0) addr=0x80103000a510

dmesg shows no EEH recovery messages:

  [  108.563768] bnx2x: [bnx2x_timer:5801(eth2)]MFW seems hanged: drv_pulse (0x9ae) != mcp_pulse (0x7fff)
  [  108.563788] bnx2x: [bnx2x_hw_stats_update:870(eth2)]NIG timer max (4294967295)
  [  108.883788] bnx2x: [bnx2x_acquire_hw_lock:2013(eth1)]lock_status 0xffffffff  resource_bit 0x1
  [  108.884407] bnx2x 0030:01:00.0 eth1: MDC/MDIO access timeout
  [  108.884976] bnx2x 0030:01:00.0 eth1: MDC/MDIO access timeout
  &lt;..&gt;

After this patch:

eeh_addr_cache_get_dev() trace shows correct physical address:

  &lt;idle&gt;-0       [001] ..s.  1043.123828: eeh_addr_cache_get_dev:
	  (eeh_addr_cache_get_dev+0xc/0xf0) addr=0x40080bc7cd8

dmesg logs shows EEH recovery getting triggerred:

  [  964.323980] bnx2x: [bnx2x_timer:5801(eth2)]MFW seems hanged: drv_pulse (0x746f) != mcp_pulse (0x7fff)
  [  964.323991] EEH: Recovering PHB#30-PE#10000
  [  964.324002] EEH: PE location: N/A, PHB location: N/A
  [  964.324006] EEH: Frozen PHB#30-PE#10000 detected
  &lt;..&gt;

Fixes: 33439620680b ("powerpc/eeh: Handle hugepages in ioremap space")
Cc: stable@vger.kernel.org # v5.3+
Reported-by: Dominic DeMarco &lt;ddemarc@us.ibm.com&gt;
Signed-off-by: Mahesh Salgaonkar &lt;mahesh@linux.ibm.com&gt;
Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/161821396263.48361.2796709239866588652.stgit@jupiter
</content>
</entry>
<entry>
<title>powerpc/eeh: Fix build failure with CONFIG_PROC_FS=n</title>
<updated>2021-03-29T02:22:14Z</updated>
<author>
<name>Michael Ellerman</name>
<email>mpe@ellerman.id.au</email>
</author>
<published>2021-03-14T09:33:00Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=7a7685acd2129e2e5d433636120b4c5038c03e51'/>
<id>urn:sha1:7a7685acd2129e2e5d433636120b4c5038c03e51</id>
<content type='text'>
The build fails with CONFIG_PROC_FS=n:

  arch/powerpc/kernel/eeh.c:1571:12: error: ‘proc_eeh_show’ defined but not used
   1571 | static int proc_eeh_show(struct seq_file *m, void *v)

Wrap proc_eeh_show() in an ifdef to avoid it.

Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20210314093300.131998-1-mpe@ellerman.id.au
</content>
</entry>
<entry>
<title>powerpc/eeh: Add a debugfs interface to check if a driver supports recovery</title>
<updated>2021-01-31T11:35:47Z</updated>
<author>
<name>Oliver O'Halloran</name>
<email>oohall@gmail.com</email>
</author>
<published>2020-11-03T05:15:12Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=9e857416833d9701a406ecd6f03a695405ada5e6'/>
<id>urn:sha1:9e857416833d9701a406ecd6f03a695405ada5e6</id>
<content type='text'>
If a PCI device's current driver implements the error handling callbacks
EEH can use them to recover the device after an error occurs. For devices
without the error handling callbacks we recover them by removing the device
and re-scanning it so the PCI core puts the device back into a known good
state.

Currently there's no way for userspace to determine if the driver supports
recovery or not which makes it difficult to write automated tests for EEH.
This patch addressing that by adding a debugfs interface for querying if
a specific device can be recovered or not.

Signed-off-by: Oliver O'Halloran &lt;oohall@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20201103051512.919333-2-oohall@gmail.com
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