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drm/i915: Set sync_seqno properly after seqno wrap 

i915_gem_handle_seqno_wrap() will zero all sync_seqnos but as the
wrap can happen inside ring->sync_to(), pre wrap seqno was
carried over and overwrote the zeroed sync_seqno.

When wrap is handled, all outstanding requests will be retired and
objects moved to inactive queue, causing their last_read_seqno to be zero.
Use this to update the sync_seqno correctly.

RING_SYNC registers after wrap will contain pre wrap values which
are >= seqno. So injecting the semaphore wait into ring completes
immediately.

Original idea for using last_read_seqno from Chris Wilson.

Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Mika Kuoppala 2012-11-28 17:18:45 +02:00 committed by Daniel Vetter
parent df2b23d979
commit 7b01e260a6
1 changed files with 5 additions and 1 deletions
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6
drivers/gpu/drm/i915/i915_gem.c
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@ -2397,7 +2397,11 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
ret = to->sync_to(to, from, seqno);
if (!ret)
from->sync_seqno[idx] = seqno;
/* We use last_read_seqno because sync_to()
* might have just caused seqno wrap under
* the radar.
*/
from->sync_seqno[idx] = obj->last_read_seqno;
return ret;
}