drm/i915: Use LRI to update the semaphore registers
The bspec was recently updated to remove the ability to update the
semaphore using the MI_SEMAPHORE_BOX command, the ability to wait upon
the semaphore value remained. Instead the advice is to update the
register using the MI_LOAD_REGISTER_IMM command. In cursory testing,
semaphores continue to function - the question is whether this fixes
some of the deadlocks where the semaphore registers contained stale
values?
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel J Blueman <daniel@quora.org>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 1aa7689..987eb5f 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -558,12 +558,9 @@
u32 seqno,
u32 mmio_offset)
{
- intel_ring_emit(ring, MI_SEMAPHORE_MBOX |
- MI_SEMAPHORE_GLOBAL_GTT |
- MI_SEMAPHORE_REGISTER |
- MI_SEMAPHORE_UPDATE);
- intel_ring_emit(ring, seqno);
+ intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
intel_ring_emit(ring, mmio_offset);
+ intel_ring_emit(ring, seqno);
}
/**