[Intel-gfx] [PATCH v5] drm/i915: Pin the ifbdev for the info->system_base GGTT mmapping

[Daniel Vetter]

On Thu, Dec 10, 2015 at 05:41:30PM +0100, Takashi Iwai wrote:
> On Thu, 10 Dec 2015 17:36:04 +0100,
> Ville Syrjälä wrote:
> > 
> > On Fri, Dec 04, 2015 at 04:05:26PM +0000, Chris Wilson wrote:
> > > 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: Only unpin the intel_fb is we allocate it. If we inherit the fb from
> > > the BIOS, we do not own the pinned vma (except for the reference we add
> > > in this patch for our access via info->screen_base).
> > > 
> > > v3: Finish balancing the vma pinning for the normal !preallocated case.
> > > 
> > > v4: Try to simplify the pinning even further.
> > > v5: Leak the VMA (cleaned up by object-free) to avoid complicated error paths.
> > > 
> > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > > Cc: "Goel, Akash" <akash.goel at intel.com>
> > > Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> > > Cc: Jesse Barnes <jbarnes at virtuousgeek.org>
> > > Cc: Lukas Wunner <lukas at wunner.de>
> > > Cc: stable at vger.kernel.org
> > 
> > This seems to have fixed my garbled text+fbcon dead after
> > suspend/hibernate issues. Well, only had the patch in for a day or so,
> > but so far so good.
> > 
> > Tested-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Takashi, don't know if you already found this patch, but it's definitely
> > something you should try as well.
> 
> Great, I'll give this a try.  Thanks!

Pulled both patches into dinq. Jani, can you please cherry-pick?

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch