[Intel-gfx] [PATCH 2/2] drm/i915: Bump pin_count to UINT_MAX.

[Chris Wilson]

On Mon, May 23, 2016 at 06:09:31PM +0200, Maarten Lankhorst wrote:
> Op 23-05-16 om 17:43 schreef Chris Wilson:
> > On Mon, May 23, 2016 at 05:09:05PM +0200, Maarten Lankhorst wrote:
> >> Op 23-05-16 om 16:25 schreef Chris Wilson:
> >>> On Mon, May 23, 2016 at 03:37:41PM +0200, Maarten Lankhorst wrote:
> >>>> With nonblocking unpin there can be many cursor pins before they're
> >>>> cleared by the next page flip.
> >>>>
> >>>> Fix this by extending pin_count to the full 32-bit to prevent a
> >>>> WARN_ON(vma->pin_count == DRM_I915_GEM_OBJECT_MAX_PIN_COUNT)
> >>> This is a hack that affects non-KMS paths. Being able to process binding
> >>> in a single operation on all architectures is something we want to
> >>> preserve.
> >>>
> >>> Why is every cursor movement generating an unpin work? Should I just
> >>> start poking registers from userspace to avoid a silly kerenl?
> >>> -Chris
> >>>
> >> All the unpin work gets batched till after the next vblank, it's not very efficient
> >> but if you want to fix it you should just add the vma to plane state already.
> > I still don't see where the flush will occur, or why vblanks would be
> > running at all for cursor updates.
> Next page flip. All cursor updates are added to flip_work list and are cleared on vblank.

Now knowing the trigger, I've written a reproducer: igt/kms_cursor_legacy
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre