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Commit 1c8b46fc authored by Chris Wilson's avatar Chris Wilson Committed by Daniel Vetter
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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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel J Blueman <daniel@quora.org>
Reviewed-by: default avatarBen Widawsky <ben@bwidawsk.net>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent ae6935dd

drivers/gpu/drm/i915/intel_ringbuffer.c

+2 −5
Original line number Diff line number Diff line
@@ -558,12 +558,9 @@ update_mboxes(struct intel_ring_buffer *ring, 
	    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);

}



/**