[Quantal][SRU] Updated i915 driver for HSW support

Tim Gardner tim.gardner at canonical.com
Mon Dec 3 14:36:04 UTC 2012

On 12/01/2012 12:13 AM, Leann Ogasawara wrote:
> BugLink: http://bugs.launchpad.net/bugs/1085245
> Given this set of patches should be well contained and really only
> affect Haswell hardware, I propose we try and pull it in for the
> upcoming Quantal kernel SRU cycle.  It will allow us to ensure we see no
> regressions on non-Haswell hardware but also allow us to start more
> widespread testing against the Haswell hardware we do have access to.
> Thanks,
> Leann

Initially I was quite conflicted about this patch set because its a bit 
difficult to asses the impact on existing platforms. Obviously we can't 
regress Haswell GPUs (because they currently don't work at all), but I 
was a bit concerned about regression potential for non-Haswell GPUs. I 
think the best way to look at this patch set is from the perspective of 
what has been changed in the core kernel, e.g., simply ignore Haswell 
specific code. You can see what has changed in the main kernel by 
looking at it thus (after applying all of the Haswell patches on top of 
'Linux' :

git log --reverse -p d45afedb9671c093e8c185da7dc84a0dc9697e91..HEAD -- 

With the exception of the patch that creates 
drivers/gpu/drm/drm_mm_hsw.c, everything else is a (mostly) benign 
addition or a bonafide bug fix. Perhaps for clarity drm_mm_hsw.c could 
be moved under the ubuntu directory?

In general, maintenance of the drm patches are going to be a giant pain 
in the ass simply because _anything_ having to do with Haswell won't be 
considered stable material by upstream (patches from 3.8), so we're 
gonna have to keep an eye out for drm patches that are applicable to our 
bastardized pile.

Have you considered dropping the whole drm stack from hsw-backport-3.6 
into the ubuntu directory with name space isolation ? Since its pretty 
close to what'll end up in 3.8, it might make maintenance simpler since 
we can relatively easily groom drm and Haswell GPU patches from 3.8 and 
subsequent stable updates. We could also isolate changes from LTS 
Quantal by turning off the config option.

I guess I'm OK with this patch set, but I would like to hear from the 
stable team.

Tim Gardner tim.gardner at canonical.com

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