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

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Message-ID: <20110616114146.4662ea2f@jbarnes-desktop>
Date:	Thu, 16 Jun 2011 11:41:46 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Dirk Gouders <gouders@...bocholt.fh-gelsenkirchen.de>
Cc:	linux-kernel@...r.kernel.org,
	Chris Wilson <chris@...is-wilson.co.uk>
Subject: Re: [2.6.39] drm/i915: blank screen on Lenovo Ideapad U160

On Thu, 16 Jun 2011 19:54:36 +0200
Dirk Gouders <gouders@...bocholt.fh-gelsenkirchen.de> wrote:

> Jesse Barnes <jbarnes@...tuousgeek.org> writes:
> 
> > On Thu, 16 Jun 2011 13:49:11 +0200
> > Dirk Gouders <gouders@...bocholt.fh-gelsenkirchen.de> wrote:
> >
> >> Some redundant information, but if I change one line at another place
> >> in the i915 code (whithout the above modification) the result is more
> >> satisfactory on my machine, because in that case the display even works
> >> after I close and reopen the lid:
> >> 
> >> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> >> index 927442a..ebb67ae 100644
> >> --- a/drivers/gpu/drm/i915/intel_bios.c
> >> +++ b/drivers/gpu/drm/i915/intel_bios.c
> >> @@ -267,7 +267,7 @@ static int intel_bios_ssc_frequency(struct drm_device *dev,
> >>         case 4:
> >>                 return alternate ? 100 : 96;
> >>         default:
> >> -               return alternate ? 100 : 120;
> >> +               return alternate ? 120 : 100;
> >>         }
> >>  }
> >
> > Does your machine also work if you set the lvds_use_ssc param to 0?
> 
> Yes, that works!
> I undid all modifications, compiled the i915 driver as a module (I am
> not sure if that is necessary) und used i915.lvds_use_ssc=0 as a
> further bootparameter, I will attach the dmesg output.
> 
> Would you say "This problem was just a case of wrong parameter usage",
> then?

No, we should be parsing the VBT differently in your case it appears.
But the simple change above will break other platforms, so it's
possible we're missing a VBT format change and need to parse it
differently depending on the version.

-- 
Jesse Barnes, Intel Open Source Technology Center
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