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

[Chris Wilson]

On Thu, Oct 08, 2015 at 01:50:21PM -0700, Wayne Boyer wrote:
> From: Chris Wilson <chris at 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/
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre