[Intel-gfx] [C220] Display goes blank with PCH PWM1 enabled warning in intel_display.c:7376/6900

[Jani Nikula]

On Mon, 10 Nov 2014, Catalin Hritcu <catalin.hritcu at gmail.com> wrote:
> On Mon, Nov 10, 2014 at 11:47 AM, Jani Nikula
> <jani.nikula at linux.intel.com> wrote:
>> On Mon, 10 Nov 2014, Catalin Hritcu <catalin.hritcu at gmail.com> wrote:
>>> Dear Intel graphics driver community,
>>>
>>> I'm a user experiencing display problems and joined this mailing list
>>> to get some help with filing a proper bug report. In particular,
>>> I'm unsure against which component I should file the following problem.
>>
>> Please file a new bug against DRM/Intel at [1].
>>
>> Reference your mail on the mailing list.
>>
>> Smells like pm refcounting problems.
>
> I've filed a new bug as instructed:
> https://bugs.freedesktop.org/show_bug.cgi?id=86105
>
>> Attach dmesg with
>> drm.debug=14 module parameter set, from boot to the problem.
>
> I'll try to produce a dmesg log with drm.debug=14 set from the boot.
> This will take a while since restarting causes the problem to go away
> and it takes days or even weeks for the problem to reappear. The
> problem is happening right now though, so if someone can suggest a way
> to pass drm.debug=14 without rebooting the machine this I could
> provide some preliminary information right away. I've tried this:

# echo 14 > /sys/module/drm/parameters/debug

Unfortunately setting that now likely does not help in figuring out how
we got into that situation to begin with. My guess is still the same;
there's some sequence that leads to one pm put too many.

BR,
Jani.


>
> [hritcu at detained i915]$ sudo sysctl drm.debug=14
> [sudo] password for hritcu:
> sysctl: cannot stat /proc/sys/drm/debug: No such file or directory
> [hritcu at detained i915]$ ls /proc/sys
> abi  debug  dev  fs  kernel  net  vm
>
> but I have no drm directory in /proc/sys.
>
> Many thanks,
> Catalin

-- 
Jani Nikula, Intel Open Source Technology Center