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This is something that we've wanted for a while now: the ability to
actually look up the respective drm_device for a given drm_dp_aux struct.
This will also allow us to transition over to using the drm_dbg_*() helpers
for debug message printing, as we'll finally have a drm_device to reference
for doing so.
Note that there is one limitation with this - because some DP AUX adapters
exist as platform devices which are initialized independently of their
respective DRM devices, one cannot rely on drm_dp_aux->drm_dev to always be
non-NULL until drm_dp_aux_register() has been called. We make sure to point
this out in the documentation for struct drm_dp_aux.
v3:
* Add WARN_ON_ONCE() to drm_dp_aux_register() if drm_dev isn't filled out
Signed-off-by: Lyude Paul <lyude@redhat.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423184309.207645-4-lyude@redhat.com
Reviewed-by: Dave Airlie <airlied@redhat.com>
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I observed this when unplugging a DP monitor whilst a computer is asleep
and then waking it up. This left DP chardev nodes still being present on
the filesystem and accessing these device nodes caused an oops because
drm_dp_aux_dev_get_by_minor() assumes a device exists if it is opened.
This can also be reproduced by creating a device node with mknod(1) and
issuing an open(2)
[166164.933198] BUG: kernel NULL pointer dereference, address: 0000000000000018
[166164.933202] #PF: supervisor read access in kernel mode
[166164.933204] #PF: error_code(0x0000) - not-present page
[166164.933205] PGD 0 P4D 0
[166164.933208] Oops: 0000 [#1] PREEMPT SMP NOPTI
[166164.933211] CPU: 4 PID: 99071 Comm: fwupd Tainted: G W
5.8.0-rc6+ #1
[166164.933213] Hardware name: LENOVO 20RD002VUS/20RD002VUS, BIOS R16ET25W
(1.11 ) 04/21/2020
[166164.933232] RIP: 0010:drm_dp_aux_dev_get_by_minor+0x29/0x70
[drm_kms_helper]
[166164.933234] Code: 00 0f 1f 44 00 00 55 48 89 e5 41 54 41 89 fc 48 c7
c7 60 01 a4 c0 e8 26 ab 30 d7 44 89 e6 48 c7 c7 80 01 a4 c0 e8 47 94 d6 d6
<8b> 50 18 49 89 c4 48 8d 78 18 85 d2 74 33 8d 4a 01 89 d0 f0 0f b1
[166164.933236] RSP: 0018:ffffb7d7c41cbbf0 EFLAGS: 00010246
[166164.933237] RAX: 0000000000000000 RBX: ffff8a90001fe900 RCX: 0000000000000000
[166164.933238] RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffffffffc0a40180
[166164.933239] RBP: ffffb7d7c41cbbf8 R08: 0000000000000000 R09: ffff8a93e157d6d0
[166164.933240] R10: 0000000000000000 R11: ffffffffc0a40188 R12: 0000000000000003
[166164.933241] R13: ffff8a9402200e80 R14: ffff8a90001fe900 R15: 0000000000000000
[166164.933244] FS: 00007f7fb041eb00(0000) GS:ffff8a9411500000(0000)
knlGS:0000000000000000
[166164.933245] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[166164.933246] CR2: 0000000000000018 CR3: 00000000352c2003 CR4: 00000000003606e0
[166164.933247] Call Trace:
[166164.933264] auxdev_open+0x1b/0x40 [drm_kms_helper]
[166164.933278] chrdev_open+0xa7/0x1c0
[166164.933282] ? cdev_put.part.0+0x20/0x20
[166164.933287] do_dentry_open+0x161/0x3c0
[166164.933291] vfs_open+0x2d/0x30
[166164.933297] path_openat+0xb27/0x10e0
[166164.933306] ? atime_needs_update+0x73/0xd0
[166164.933309] do_filp_open+0x91/0x100
[166164.933313] ? __alloc_fd+0xb2/0x150
[166164.933316] do_sys_openat2+0x210/0x2d0
[166164.933318] do_sys_open+0x46/0x80
[166164.933320] __x64_sys_openat+0x20/0x30
[166164.933328] do_syscall_64+0x52/0xc0
[166164.933336] entry_SYSCALL_64_after_hwframe+0x44/0xa9
(gdb) disassemble drm_dp_aux_dev_get_by_minor+0x29
Dump of assembler code for function drm_dp_aux_dev_get_by_minor:
0x0000000000017b10 <+0>: callq 0x17b15 <drm_dp_aux_dev_get_by_minor+5>
0x0000000000017b15 <+5>: push %rbp
0x0000000000017b16 <+6>: mov %rsp,%rbp
0x0000000000017b19 <+9>: push %r12
0x0000000000017b1b <+11>: mov %edi,%r12d
0x0000000000017b1e <+14>: mov $0x0,%rdi
0x0000000000017b25 <+21>: callq 0x17b2a <drm_dp_aux_dev_get_by_minor+26>
0x0000000000017b2a <+26>: mov %r12d,%esi
0x0000000000017b2d <+29>: mov $0x0,%rdi
0x0000000000017b34 <+36>: callq 0x17b39 <drm_dp_aux_dev_get_by_minor+41>
0x0000000000017b39 <+41>: mov 0x18(%rax),%edx <=========
0x0000000000017b3c <+44>: mov %rax,%r12
0x0000000000017b3f <+47>: lea 0x18(%rax),%rdi
0x0000000000017b43 <+51>: test %edx,%edx
0x0000000000017b45 <+53>: je 0x17b7a <drm_dp_aux_dev_get_by_minor+106>
0x0000000000017b47 <+55>: lea 0x1(%rdx),%ecx
0x0000000000017b4a <+58>: mov %edx,%eax
0x0000000000017b4c <+60>: lock cmpxchg %ecx,(%rdi)
0x0000000000017b50 <+64>: jne 0x17b76 <drm_dp_aux_dev_get_by_minor+102>
0x0000000000017b52 <+66>: test %edx,%edx
0x0000000000017b54 <+68>: js 0x17b6d <drm_dp_aux_dev_get_by_minor+93>
0x0000000000017b56 <+70>: test %ecx,%ecx
0x0000000000017b58 <+72>: js 0x17b6d <drm_dp_aux_dev_get_by_minor+93>
0x0000000000017b5a <+74>: mov $0x0,%rdi
0x0000000000017b61 <+81>: callq 0x17b66 <drm_dp_aux_dev_get_by_minor+86>
0x0000000000017b66 <+86>: mov %r12,%rax
0x0000000000017b69 <+89>: pop %r12
0x0000000000017b6b <+91>: pop %rbp
0x0000000000017b6c <+92>: retq
0x0000000000017b6d <+93>: xor %esi,%esi
0x0000000000017b6f <+95>: callq 0x17b74 <drm_dp_aux_dev_get_by_minor+100>
0x0000000000017b74 <+100>: jmp 0x17b5a <drm_dp_aux_dev_get_by_minor+74>
0x0000000000017b76 <+102>: mov %eax,%edx
0x0000000000017b78 <+104>: jmp 0x17b43 <drm_dp_aux_dev_get_by_minor+51>
0x0000000000017b7a <+106>: xor %r12d,%r12d
0x0000000000017b7d <+109>: jmp 0x17b5a <drm_dp_aux_dev_get_by_minor+74>
End of assembler dump.
(gdb) list *drm_dp_aux_dev_get_by_minor+0x29
0x17b39 is in drm_dp_aux_dev_get_by_minor (drivers/gpu/drm/drm_dp_aux_dev.c:65).
60 static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
61 {
62 struct drm_dp_aux_dev *aux_dev = NULL;
63
64 mutex_lock(&aux_idr_mutex);
65 aux_dev = idr_find(&aux_idr, index);
66 if (!kref_get_unless_zero(&aux_dev->refcount))
67 aux_dev = NULL;
68 mutex_unlock(&aux_idr_mutex);
69
(gdb) p/x &((struct drm_dp_aux_dev *)(0x0))->refcount
$8 = 0x18
Looking at the caller, checks on the minor are pushed down to
drm_dp_aux_dev_get_by_minor()
static int auxdev_open(struct inode *inode, struct file *file)
{
unsigned int minor = iminor(inode);
struct drm_dp_aux_dev *aux_dev;
aux_dev = drm_dp_aux_dev_get_by_minor(minor); <====
if (!aux_dev)
return -ENODEV;
file->private_data = aux_dev;
return 0;
}
Fixes: e94cb37b34eb ("drm/dp: Add a drm_aux-dev module for reading/writing dpcd registers.")
Cc: <stable@vger.kernel.org> # v4.6+
Signed-off-by: Zwane Mwaikambo <zwane@yosper.io>
Reviewed-by: Lyude Paul <lyude@redhat.com>
[added Cc to stable]
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/alpine.DEB.2.21.2010122231070.38717@montezuma.home
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Instead of having drm_dp_dpcd_read/write and
drm_dp_mst_dpcd_read/write as entry points into the
aux code, have drm_dp_dpcd_read/write handle both.
This means that DRM drivers can make MST DPCD read/writes.
v2: Fix spacing
v3: Dump dpcd access on MST read/writes
v4: Fix calling wrong function on DPCD write
v5: delete deprecated include of drmP.h
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: David Francis <David.Francis@amd.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
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All available downstream ports - physical and logical - are exposed for
each MST device. They are listed in /dev/, following the same naming
scheme as SST devices by appending an incremental ID.
Although all downstream ports are exposed, only some will work as
expected. Consider the following topology:
+---------+
| ASIC |
+---------+
Conn-0|
|
+----v----+
+----| MST HUB |----+
| +---------+ |
| |
|Port-1 Port-2|
+-----v-----+ +-----v-----+
| MST | | SST |
| Display | | Display |
+-----------+ +-----------+
|Port-1
x
MST Path | MST Device
----------+----------------------------------
sst:0 | MST Hub
mst:0-1 | MST Display
mst:0-1-1 | MST Display's disconnected DP out
mst:0-1-8 | MST Display's internal sink
mst:0-2 | SST Display
On certain MST displays, the upstream physical port will ACK DPCD reads.
However, reads on the local logical port to the internal sink will
*NAK*. i.e. reading mst:0-1 ACKs, but mst:0-1-8 NAKs.
There may also be duplicates. Some displays will return the same GUID
when reading DPCD from both mst:0-1 and mst:0-1-8.
There are some device-dependent behavior as well. The MST hub used
during testing will actually *ACK* read requests on a disconnected
physical port, whereas the MST displays will NAK.
In light of these discrepancies, it's simpler to expose all downstream
ports - both physical and logical - and let the user decide what to use.
v3 changes:
* Change WARN_ON_ONCE -> DRM_ERROR on dpcd read errors
* Docstring and cosmetic fixes
v2 changes:
Moved remote aux device (un)registration to new mst connector late
register and early unregister helpers. Drivers should call these from
their own mst connector function hooks.
This is to solve an issue during driver unload, where mst connector
devices are unregistered before the remote aux devices are. In a setup
where aux devices are created as children of connector devices, the aux
device would be removed too early, and uncleanly. Doing so in
early_unregister solves this issue, as that is called before connector
unregistration.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190723232808.28128-3-sunpeng.li@amd.com
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In preparation for adding aux devices for DP MST, make the IDR
non-cyclic. That way, hotplug cycling MST devices won't needlessly
increment the minor version index.
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190723232808.28128-2-sunpeng.li@amd.com
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Continue to get rid of drmP.h. Add minimal includes to build. Sort
includes while at it.
Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190506095248.20874-1-jani.nikula@intel.com
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The old wait_on_atomic_t() is going to get removed, use the more
flexible wait_var_event() API instead.
Unlike wake_up_atomic_t(), wake_up_var() will issue the wakeup
even if the variable is not 0.
No change in functionality.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Make wait_on_atomic_t() pass the TASK_* mode onto its action function as an
extra argument and make it 'unsigned int throughout.
Also, consolidate a bunch of identical action functions into a default
function that can do the appropriate thing for the mode.
Also, change the argument name in the bit_wait*() function declarations to
reflect the fact that it's the mode and not the bit number.
[Peter Z gives this a grudging ACK, but thinks that the whole atomic_t wait
should be done differently, though he's not immediately sure as to how]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
cc: Ingo Molnar <mingo@kernel.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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They're only used internally within the dp helpers. Also nuke the
kerneldoc (we only document the driver interface in the drm shared
functions). And move the header file from the public include/
directory to the source files into drm_crtc_helper_internal.h, similar
to how we already have drm_crtc_internal.h.
While at it also move drm_fb_helper_modinit since that belongs in
there, too.
I noticed this all since I spotted kerneldoc which wasn't pulled into
the rst templates.
v2: Update Copyright date.
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471034937-651-16-git-send-email-daniel.vetter@ffwll.ch
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If class_create() fails, there is no need for class_destroy().
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1467237135-13075-1-git-send-email-khoroshilov@ispras.ru
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Let's be nice and interrupt the dpcd aux-dev reads/writes when there's
a signal pending. Much nicer if the user can hit ^C instead of having to
sit around waiting for the read/write to finish.
time dd if=/dev/drm_dp_aux0 bs=$((1024*1024))
^C
before:
real 0m34.681s
user 0m0.003s
sys 0m6.880s
after:
real 0m0.222s
user 0m0.006s
sys 0m0.057s
Cc: Rafael Antognolli <rafael.antognolli@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461786225-7790-1-git-send-email-ville.syrjala@linux.intel.com
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This module is heavily based on i2c-dev. Once loaded, it provides one
dev node per DP AUX channel, named drm_dp_auxN, where N is an integer.
It's possible to know which connector owns this aux channel by looking
at the respective sysfs /sys/class/drm_aux_dev/drm_dp_auxN/connector, if
the connector device pointer was correctly set in the aux helper struct.
Two main operations are provided on the registers read and write. The
address of the register to be read or written is given using lseek. The
seek position is updated upon read or write.
v2:
- lseek is used to select the register to read/write
- read/write are used instead of ioctl
- no blocking_notifier is used, just a direct callback
v3:
- use drm_dp_aux_dev prefix for public functions
- chardev is named drm_dp_auxN
- read/write don't allocate a buffer anymore, and transfer up to 16 bytes a
time
- remove notifier list from the implementation
- option on menuconfig is now a boolean
- add inline stub functions to avoid breakage when this option is disabled
v4:
- fix build system changes - actually disable this module when not selected.
v5:
- Use kref to avoid device closing while still in use
- Don't use list, use an idr for storing aux_dev
- Remove "connector" attribute
- set aux.dev to the connector drm_connector device, instead of
drm_device
v6:
- Use atomic_t for usage count
- Use a mutex instead of spinlock for idr lock
- Destroy chardev immediately on unregister
- other minor suggestions from Ville
v7:
- style fixes
- error handling fixes
v8:
- more error handling fixes
v9:
- remove module_init and module_exit, and add drm_dp_aux_dev_init/exit
to drm_kms_helper_init/exit.
Signed-off-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1453417821-2811-3-git-send-email-rafael.antognolli@intel.com
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Lyude Paul
Zwane Mwaikambo
David Francis
Ville Syrjälä
Leo Li
Jani Nikula
Peter Zijlstra
David Howells
Al Viro
Daniel Vetter
Alexey Khoroshilov
Rafael Antognolli