linux-kernel - Re: [3.0-rc1] i915: blank screen on Lenovo Ideapad U160

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Date:	Tue, 31 May 2011 21:29:15 +0200
From:	Dirk Gouders <gouders@...bocholt.fh-gelsenkirchen.de>
To:	"Robert P. J. Day" <rpjday@...shcourse.ca>
Cc:	linux-kernel@...r.kernel.org,
	Chris Wilson <chris@...is-wilson.co.uk>
Subject: Re: [3.0-rc1] i915: blank screen on Lenovo Ideapad U160

Dirk Gouders <gouders@...bocholt.fh-gelsenkirchen.de> writes:

> "Robert P. J. Day" <rpjday@...shcourse.ca> writes:
>
>> On Tue, 31 May 2011, Dirk Gouders wrote:
>>
>>> Hello,
>>>
>>> I tested 3.0.0-rc1 on my notebook which has never been the best friend
>>> of the i915 driver.  With linux-2.6.38-gentoo-r4 it has the problem
>>> that the screen remains blank after the lid is closed and reopened, but
>>> that problem I can live with.  With 3.0.0-r1 I am back to a former
>>> problem that the screen goes (and remains) blank while booting.
>>>
>>> The next step I will do is to test linux-2.6.39-gentoo, probably I
>>> did not notice information that I have to adjust boot parameters or the
>>> kernel config?
>>
>>   based on my having lived through the i915 "black screen of death",
>> pulling out my handy "git bisect" and with advice from chris wilson,
>> these days, i simply apply this patch to the source:
>>
>> diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
>> index d2c7104..a1a5d03 100644
>> --- a/drivers/gpu/drm/i915/intel_opregion.c
>> +++ b/drivers/gpu/drm/i915/intel_opregion.c
>> @@ -152,6 +152,8 @@ static u32 asle_set_backlight(struct drm_device *dev, u32 bclp)
>>  	struct opregion_asle *asle = dev_priv->opregion.asle;
>>  	u32 max;
>>
>> +return ASLE_BACKLIGHT_FAILED; // rday
>> +
>>  	if (!(bclp & ASLE_BCLP_VALID))
>>  		return ASLE_BACKLIGHT_FAILED;
>>
>>
>>   i tried taking it out a couple of times and immediately got the same
>> i915-related problem so until i hear differently, the patch stays in.
>
> Thanks for the hint.  I tested the patch with 3.0.0-rc1 and
> unfortunately the symptoms remain the same.
>
> Meanwhile, I tested 2.6.39-gentoo as well and it also causes that
> problem.  So, this is not really a (new) 3.0.0-rc1 issue.
>
> Best regards,
>
> Dirk

Your patch reminded me of another patch of Chris that caused problems
for several other people, but manually applied to the changed context in
3.0.0-rc1 again works for me:

--- linux-3.0-rc1/drivers/gpu/drm/i915/intel_bios.c     2011-05-30 02:43:36.000000000 +0200
+++ /usr/src/linux-3.0-rc1/drivers/gpu/drm/i915/intel_bios.c    2011-05-31 20:53:35.000000000 +0200
@@ -267,7 +267,7 @@
        case 4:
                return alternate ? 100 : 96;
        default:
-               return alternate ? 100 : 120;
+               return alternate ? 120 : 100;
        }
 }

The strange thing is that I am pretty sure that I did not have to modify
2.6.28-gentoo{,-r4} what I at that time also reported here:
https://bugs.freedesktop.org/show_bug.cgi?id=31596

Best regards,

Dirk
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