linux-kernel - Re: [2.6.39] drm/i915: blank screen on Lenovo Ideapad U160

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Date:	Mon, 13 Jun 2011 23:21:12 +0200
From:	Dirk Gouders <gouders@...bocholt.fh-gelsenkirchen.de>
To:	linux-kernel@...r.kernel.org
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Chris Wilson <chris@...is-wilson.co.uk>
Subject: Re: [2.6.39] drm/i915: blank screen on Lenovo Ideapad U160

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

> 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

For completeness I want to report that I did a bisect and found out that
the following commit seems to be the one that reintroduced the problem
that I have to manually patch the kernel to avoid a blank screen
(with backlight turned on) during boot:

47a05eca72991039e788b25232061f9c9df9ec23 is the first bad commit
commit 47a05eca72991039e788b25232061f9c9df9ec23
Author: Jesse Barnes <jbarnes@...tuousgeek.org>
Date:   Mon Feb 7 13:46:40 2011 -0800

    drm/i915: disable PCH ports if needed when disabling a CRTC
    
    Disable any PCH ports associated with a pipe when disabling it.  This
    should prevent transcoder disable failures due to ports still being on.
    
    Signed-off-by: Jesse Barnes <jbarnes@...tuousgeek.org>
    [ickle: introduce *_PIPE_ENABLED() macro]
    Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>

:040000 040000 2c7c54cceb89821941943614cede86c4a2c2a8bc 9382527ee169beb54a10eb0afe8a69d418025c2e M      drivers

Dirk
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