LP:919350 Regression Commit Identified

[Tim Gardner]

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
-- 
Tim Gardner tim.gardner at canonical.com