Re: [git pull] drm fixes

Dave Airlie
2010-12-23T06:03:19Z

On Thu, Dec 23, 2010 at 1:54 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Wed, Dec 22, 2010 at 8:59 AM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
>> On Wed, 22 Dec 2010 17:24:36 +0100, Takashi Iwai <tiwai@suse.de> wrote:
>>> The commit 448f53a1ede54eb854d036abf54573281412d650
>>>   drm/i915/bios: Reverse order of 100/120 Mhz SSC clocks
>>>
>>> causes a regression on a SandyBridge machine here.
>>> The laptop display (LVDS) becomes blank.  Reverting the commit fixes
>>> the problem.
>>
>> The question is whose BIOS is wrong?
>
> I don't think so.
>
>>                         The Lenovo U160's or the
>> Sandybridge SDV? And why does it work for that other OS? <Insert
>> rhetorical question of the day here.>
>
> Quite frankly, I don't think the question should *ever* be "whose BIOS
> is wrong?"
>
> You should always take for granted that the BIOS is wrong. It's not a
> question of "blame the BIOS", it's a question of facts of life.
>
> It's 100% pointless to point fingers and say "the HP BIOS is wrong" or
> "the Lenovo BIOS is wrong". Buggy BIOSes happen. ALWAYS. Any code that
> relies on the BIOS to such a degree that it either works or not based
> on it is by definition broken.
>
> Why does that code need to figure out some LVDS clock from the BIOS?
> Why can't the code look at the actual hardware state or similar, since
> presumably the screen is on after boot. THAT we can rely on, since a
> BIOS that doesn't initialize LVDS is not going to ever ship even as
> pre-release.
>

I've no idea but since this is spread-spectrum related the bios may not enable
spread-spectrum on the panel, though really the question is as always, what does
Windows do.

Dave.
>                        Linus
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