On Fri, Oct 02, 2015 at 10:16:26PM +0000, Boyer, Wayne wrote:
> On 8/26/15, 1:23 AM, Deepak <deepak.s@xxxxxxxxxxxxxxx> wrote:
>
>
> >
> >
> >On 08/25/2015 10:18 PM, 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.
> >
> >Yup this is a critical fix :) by keeping the internal FB pinned we avoid
> >alloc of buffer within same FB GTT offset
> >Reviewed-by: Deepak S <deepak.s@xxxxxxxxxxxxxxx>
>
> Daniel,
>
> Is there anything else that needs to happen before this gets pulled in?
Someone needs to send out the rebased-on-upstream version. The patches
have been merged but then had to be dropped again since they where based
on top of Chris' tree.
-Daniel
>
> Thanks,
> Wayne
>
> >
> >> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> >> Cc: "Goel, Akash" <akash.goel@xxxxxxxxx>
> >> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> >> Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
> >> Cc: stable@xxxxxxxxxxxxxxx
> >> ---
> >> drivers/gpu/drm/i915/intel_fbdev.c | 15 +++++++++++++++
> >> 1 file changed, 15 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c
> >>b/drivers/gpu/drm/i915/intel_fbdev.c
> >> index 96476d7d7ed2..082f2938ec97 100644
> >> --- a/drivers/gpu/drm/i915/intel_fbdev.c
> >> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> >> @@ -215,6 +215,16 @@ static int intelfb_create(struct drm_fb_helper
> >>*helper,
> >> obj = intel_fb->obj;
> >> size = obj->base.size;
> >>
> >> + /* The fb constructor will have already pinned us (or inherited a
> >> + * GGTT region from the BIOS) suitable for a scanout, so
> >> + * this should just be a no-op and increment the pin count for the
> >> + * fbdev mmapping. It does have a useful side-effect of validating
> >> + * the pin for fbdev's use via a GGTT mmapping.
> >> + */
> >> + ret = i915_gem_object_ggtt_pin(obj, NULL, 0, PIN_MAPPABLE);
> >> + if (ret)
> >> + goto out_unlock;
> >> +
> >> info = drm_fb_helper_alloc_fbi(helper);
> >> if (IS_ERR(info)) {
> >> ret = PTR_ERR(info);
> >> @@ -274,6 +284,9 @@ static int intelfb_create(struct drm_fb_helper
> >>*helper,
> >> out_destroy_fbi:
> >> drm_fb_helper_release_fbi(helper);
> >> out_unpin:
> >> + /* Once for info->screen_base mmaping... */
> >> + i915_gem_object_ggtt_unpin(obj);
> >> + /* ...and once for the intel_fb */
> >> i915_gem_object_ggtt_unpin(obj);
> >> drm_gem_object_unreference(&obj->base);
> >> out_unlock:
> >> @@ -514,6 +527,8 @@ static const struct drm_fb_helper_funcs
> >>intel_fb_helper_funcs = {
> >> static void intel_fbdev_destroy(struct drm_device *dev,
> >> struct intel_fbdev *ifbdev)
> >> {
> >> + /* Release the pinning for the info->screen_base mmaping. */
> >> + i915_gem_object_ggtt_unpin(ifbdev->fb->obj);
> >>
> >> drm_fb_helper_unregister_fbi(&ifbdev->helper);
> >> drm_fb_helper_release_fbi(&ifbdev->helper);
> >
> >_______________________________________________
> >Intel-gfx mailing list
> >Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> >http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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