I didn't test the patch yet. I will do. But even without testing I can
tell you that it will work (It will not crash).
Currently when the crash occurs, all screens remain black after resume.
I'm not able to login with ssh neither. And logs end before the
suspend. So the crash seems to be some kind of kernel panic.
Matthieu
On Tue, Nov 8 2022 at 01:27:33 PM +0200, Jani Nikula
<jani.nikula@xxxxxxxxx> wrote:
On Sun, 06 Nov 2022, Matthieu CHARETTE <matthieu.charette@xxxxxxxxx>
wrote:
Hi,
Can you tell me what are we waiting for? Maybe I can help.
Have you tried the patch? Is it an improvement over the status quo?
The "crash" is still ambiguous to me. Do you observe it with the
patch?
Do you have logs? Etc.
BR,
Jani.
Thanks.
Matthieu
On Wed, Oct 12 2022 at 07:16:29 PM +0200, Matthieu CHARETTE
<matthieu.charette@xxxxxxxxx> wrote:
By crash, I mean that an error is returned here:
https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux.git/+/refs/heads/master/drivers/gpu/drm/drm_edid_load.c#195
I don't really know what happens next, but on my machine the
built-in
screen and the external remains dark. Also the kernel seems to
freeze. I suspect a kernel panic, but I'm not sure. Anyway, the
error
is definitely not well handled, and a fix would be great.
Also, request_firmware() will crash if called for the first time on
the resume path because the file system isn't reachable on the
resume
process. And no cache is available for this firmware. So I guess
that
in this case, request_firmware() returns an error.
Suspend-plug-resume case is not my priority nether as long as it
doesn't make the system crash (Which is currently the case).
On Wed, Oct 12 2022 at 11:25:59 AM +0300, Jani Nikula
<jani.nikula@xxxxxxxxx> wrote:
On Tue, 11 Oct 2022, Matthieu CHARETTE
<matthieu.charette@xxxxxxxxx>
wrote:
Currently the EDID is requested during the resume. But since
it's
requested too early, this means before the filesystem is
mounted,
the
firmware request fails. This make the DRM driver crash when
resuming.
This kind of issue should be prevented by the firmware caching
process
which cache every firmware requested for the next resume. But
since we
are using a temporary device, the firmware isn't cached on
suspend
since the device doesn't work anymore.
When using a non temporary device to get the EDID, the firmware
will
be cached on suspend for the next resume. So requesting the
firmware
during resume will succeed.
But if the firmware has never been requested since the boot,
this
means that the monitor isn't plugged since the boot. The kernel
will
not be caching the EDID. So if we plug the monitor while the
machine
is suspended. The resume will fail to load the firmware. And the
DRM
driver will crash.
So basically, your fix should solve the issue except for the
case
where the monitor hasn't been plugged since boot and is plugged
while
the machine is suspended.
I hope I was clear. Tell me if I wasn't. I'm not really good at
explaining.
That was a pretty good explanation. The only thing I'm missing is
what
the failure mode is exactly when you claim the driver will crash.
Why
would request_firmware() "crash" if called for the first time on
the
resume path?
I'm not sure I care much about not being able to load the firmware
EDID
in the suspend-plug-resume case (as this can be remedied with a
subsequent modeset), but obviously any errors need to be handled
gracefully, without crashing.
BR,
Jani.
--
Jani Nikula, Intel Open Source Graphics Center
--
Jani Nikula, Intel Open Source Graphics Center
