Re: [PATCH] drm/i915: Pin the ifbdev for the info->system_base GGTT mmapping

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 09 Oct 2015, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> On Thu, Oct 08, 2015 at 01:50:21PM -0700, Wayne Boyer wrote:
>> From: Chris Wilson <chris@chris-wilson.co.uk>
>> 
>> A long time ago (before 3.14) we relied on a permanent pinning of the
>> ifbdev to lock the fb in place inside the GGTT. However, the
>> introduction of stealing the BIOS framebuffer and reusing its address in
>> the GGTT for the fbdev has muddied waters and we use an inherited fb.
>> However, the inherited fb is only pinned whilst it is active and we no
>> longer have an explicit pin for the info->system_base mmapping used by
>> the fbdev. The result is that after some aperture pressure the fbdev may
>> be evicted, but we continue to write the fbcon into the same GGTT
>> address - overwriting anything else that may be put into that offset.
>> The effect is most pronounced across suspend/resume as
>> intel_fbdev_set_suspend() does a full clear over the whole scanout.
>> 
>> v2: rebased on latest nightly (Wayne)
>> v3: changed i915_gem_object_ggtt_pin() to i915_gem_obj_ggtt_pin() based
>> on Chris' review. (Wayne)
>
> Note that this patch also depends on the
>
> 	drm/i915: Set the map-and-fenceable flag for preallocated objects
>
> fix as well
> http://patchwork.freedesktop.org/patch/58026/

Jesse, please provide your Tested-by on that plus this patch, since you
reported the breakage [1] that got the two patches reverted in the first
place.

Thanks,
Jani.


[1] http://mid.gmane.org/55DF3886.1060001@virtuousgeek.org

> -Chris
>
> -- 
> Chris Wilson, Intel Open Source Technology Centre
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-- 
Jani Nikula, Intel Open Source Technology Center
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