[Intel-gfx] Trouble with dell latitude E6420

[Georg Grabler]

It's fixed in 3.5rc4.
And I patched my 3.4 kernel with the commit of keith. The problem was
gone afterwards as well.

Kind regards,
Georg

On Thu, Jun 28, 2012 at 8:23 PM, Giacomo Comes <comes at naic.edu> wrote:
> On Thu, Jun 28, 2012 at 07:52:18AM +0200, Takashi Iwai wrote:
>> At Tue, 26 Jun 2012 15:08:32 -0400,
>> Giacomo Comes wrote:
>> >
>> > I have a dell latitude E6420 with Sandybridge Mobile (GT2).
>> > Since I got it (about one year ago), it has been a nightmare to run linux on it.
>> > At the beginning I installed openSUSE 11.4 (kernel 2.6.37.6) and the laptop
>> > would freeze almost immediately. After that I waited for newer kernels in order to
>> > see if things would improve. They did improve indeed and finally with kernel 3.0
>> > I was able to run linux (openSUSE 11.4) without laptop freeze or screen issue.
>> > Unfortunately, the only kernel that works with my laptop is 3.0. Newer kernel
>> > (3.1, 3.2, 3.3 and 3.4) do not work.
>> > This is what happen if I run kernel 2.6.39, 3.1, 3.2, 3.3 and 3.4:
>> > The laptop boot and does the boot process fine. At the end of the boot process X
>> > starts and here the problem appears (about 50% of the times):
>> > the screen goes black on the left side (about 2/3 of the whole screen) with white
>> > stripes to the right side (the remaining 1/3).
>> > The laptop is not dead: I can remotely login or I can perform a clean shutdown
>> > if I press the power button, but the screen is totally dead.
>> > Another strange issue is that after a bad boot (with the black screen) at the
>> > next reboot the screen will start to flicker. The flickering will last some time
>> > and it will become less intense as the time goes until it will disappear completely.
>> > The funny thing is that the intensity of flicker depends on how long I keep the
>> > black screen. If, after the boot process, the black screen appears and I reboot
>> > the laptop immediately, then the flicked is moderate and it disappear after
>> > 1 or 2 minutes. If I keep the black screen for 1 minute or more, then after the
>> > reboot the flicker is very intense and it takes much more to fade.
>>
>> This reminds me of a similar bug I've seen on HP laptops with HD+
>> (1600x900) monitors.  Could you check whether the patch below helps?
>>
>> Note that it just avoids entering to the wrong mode.  If your laptop
>> already starts flickering, at first recover from the flickering state,
>> apply the patch, and reboot/test.
>>
>>
>> Takashi
>>
>> ---
>> diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
>> index 08eb04c..3f61bba 100644
>> --- a/drivers/gpu/drm/i915/intel_lvds.c
>> +++ b/drivers/gpu/drm/i915/intel_lvds.c
>> @@ -413,7 +413,7 @@ static void intel_lvds_prepare(struct drm_encoder *encoder)
>>        * the panel fitter. However at all other times we can just reset
>>        * the registers regardless.
>>        */
>> -     if (!HAS_PCH_SPLIT(encoder->dev) && intel_lvds->pfit_dirty)
>> +     /*if (!HAS_PCH_SPLIT(encoder->dev) && intel_lvds->pfit_dirty)*/
>>               intel_lvds_disable(intel_lvds);
>>  }
>>
>
> This patch seems to fix the problem. I will regularly run a kernel with
> this patch and report if I see any other issue.
>
> Giacomo
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