LP:919350 Regression Commit Identified

[Brad Figg]

On 01/27/2012 04:41 AM, Tim Gardner wrote:
> On 01/27/2012 04:51 AM, Herton Ronaldo Krzesinski wrote:
>> On Thu, Jan 26, 2012 at 01:41:48PM -0700, Tim Gardner wrote:
>>> On 01/26/2012 01:18 PM, Joseph Salisbury wrote:
>>>> Hi Tim and Leann,
>>>>
>>>> The commit that caused the regression for bug 919350[1] has been
>>>> identified:
>>>>
>>>> e9925217e61dd3594f81b415f2b7e077426f208f
>>
>> The same change on oneiric is causing an issue on Precise as well, but a
>> different one (reported to be on resume from suspend):
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/917330
>>
>> So 3.2 also presents a regression, but in a different way, and is
>> already being worked upstream to be fixed (reported also here:
>> https://lkml.org/lkml/2012/1/21/66, initial fix here:
>> http://www.mail-archive.com/intel-gfx@lists.freedesktop.org/msg07955.html)
>>
>> The reports on bug 919350 is a different regression (no screen on boot),
>> and people there says that 3.2 works fine. I didn't find any problem in
>> the backport, except that it still uses (doesn't change)
>> dev_priv->edp.bpp, while in upstream this code changed. I guess this bpp
>> is low to make the link value less than it should be, resulting in the
>> failure later (wrong link * lanes selection).
>>
>> May be the backport for 3.0 requires also commits
>> 858fa03527ded333dc5701f546bd5d1b5d7515ad and
>> 89c6143263ef8e14e42e17324a234418d8030b10 (with this last one changed
>> later to not use intel_crtc->bpp as it causes the later resume from
>> suspend issue in 3.2).
>>
>> But I tend that we should just revert the backport from oneiric, even if
>> bringing back bug 899598 (better a low resolution than no screen at all),
>> we are already bringing to many changes to a stable release and
>> diverging. Let me know what you think, I can send a revert for the
>> oneiric kernel, or ask reporters on 919350 to try the backport again
>> plus the additional changes.
>>
>
>
> Reverting would be my inclination.
>
> rtg

I concur. Lets get this out of Oneiric and get it respun. We can
get this out in this cycle.

Brad
-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com