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Commit ddd4dbc6 authored by Rodrigo Vivi's avatar Rodrigo Vivi Committed by Daniel Vetter
Browse files

drm/i915: Updating comments. 



ring index calculation table was out of date after other rings were added,
although the formula is flexible and scale when adding new rings.

So this patch just update the comments and add a brief explanation
why to use sync_seqno[ring index].

Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: default avatarBen Widawsky <ben@bwidawsk.net>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent f7b64236

drivers/gpu/drm/i915/i915_gem.c

+2 −0
Original line number Diff line number Diff line
@@ -2842,6 +2842,8 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj, 
	idx = intel_ring_sync_index(from, to);



	seqno = obj->last_read_seqno;

	/* Optimization: Avoid semaphore sync when we are sure we already

	 * waited for an object with higher seqno */

	if (seqno <= from->semaphore.sync_seqno[idx])

		return 0;

drivers/gpu/drm/i915/intel_ringbuffer.h

+5 −3
Original line number Diff line number Diff line
@@ -238,9 +238,11 @@ intel_ring_sync_index(struct intel_engine_cs *ring, 
	int idx;



	/*

	 * cs -> 0 = vcs, 1 = bcs

	 * vcs -> 0 = bcs, 1 = cs,

	 * bcs -> 0 = cs, 1 = vcs.

	 * rcs -> 0 = vcs, 1 = bcs, 2 = vecs, 3 = vcs2;

	 * vcs -> 0 = bcs, 1 = vecs, 2 = vcs2, 3 = rcs;

	 * bcs -> 0 = vecs, 1 = vcs2. 2 = rcs, 3 = vcs;

	 * vecs -> 0 = vcs2, 1 = rcs, 2 = vcs, 3 = bcs;

	 * vcs2 -> 0 = rcs, 1 = vcs, 2 = bcs, 3 = vecs;

	 */



	idx = (other - ring) - 1;