drm/i915: Initialize legacy semaphores from engine hw id indexed array

Build the legacy semaphore initialisation array using the engine
hardware ids instead of driver internal ones. This makes the
static array size dependent only on the number of gen6 semaphore
engines.

Also makes the per-engine semaphore wait and signal tables
hardware id indexed saving some more space.

v2: Refactor I915_GEN6_NUM_ENGINES to GEN6_SEMAPHORE_LAST. (Chris Wilson)
v3: More polish. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <[e-mail]>
Reviewed-by: Chris Wilson <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/i915/intel_ringbuffer.c

···
 {
 	struct intel_ring *ring = req->ring;
 	struct drm_i915_private *dev_priv = req->i915;
-	struct intel_engine_cs *useless;
-	enum intel_engine_id id;
+	struct intel_engine_cs *engine;
 	int ret, num_rings;
 
 	num_rings = INTEL_INFO(dev_priv)->num_rings;
···
 	if (ret)
 		return ret;
 
-	for_each_engine_id(useless, dev_priv, id) {
-		i915_reg_t mbox_reg = req->engine->semaphore.mbox.signal[id];
+	for_each_engine(engine, dev_priv) {
+		i915_reg_t mbox_reg;
 
+		if (!(BIT(engine->hw_id) & GEN6_SEMAPHORES_MASK))
+			continue;
+
+		mbox_reg = req->engine->semaphore.mbox.signal[engine->hw_id];
 		if (i915_mmio_reg_valid(mbox_reg)) {
 			intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
 			intel_ring_emit_reg(ring, mbox_reg);
···
 	u32 dw1 = MI_SEMAPHORE_MBOX |
 		  MI_SEMAPHORE_COMPARE |
 		  MI_SEMAPHORE_REGISTER;
-	u32 wait_mbox = signal->engine->semaphore.mbox.wait[req->engine->id];
+	u32 wait_mbox = signal->engine->semaphore.mbox.wait[req->engine->hw_id];
 	int ret;
 
 	WARN_ON(wait_mbox == MI_SEMAPHORE_SYNC_INVALID);
···
 		 * initialized as INVALID.  Gen8 will initialize the
 		 * sema between VCS2 and RCS later.
 		 */
-		for (i = 0; i < I915_NUM_ENGINES; i++) {
+		for (i = 0; i < GEN6_NUM_SEMAPHORES; i++) {
 			static const struct {
 				u32 wait_mbox;
 				i915_reg_t mbox_reg;
-			} sem_data[I915_NUM_ENGINES][I915_NUM_ENGINES] = {
-				[RCS] = {
-					[VCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_RV,  .mbox_reg = GEN6_VRSYNC },
-					[BCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_RB,  .mbox_reg = GEN6_BRSYNC },
-					[VECS] = { .wait_mbox = MI_SEMAPHORE_SYNC_RVE, .mbox_reg = GEN6_VERSYNC },
+			} sem_data[GEN6_NUM_SEMAPHORES][GEN6_NUM_SEMAPHORES] = {
+				[RCS_HW] = {
+					[VCS_HW] =  { .wait_mbox = MI_SEMAPHORE_SYNC_RV,  .mbox_reg = GEN6_VRSYNC },
+					[BCS_HW] =  { .wait_mbox = MI_SEMAPHORE_SYNC_RB,  .mbox_reg = GEN6_BRSYNC },
+					[VECS_HW] = { .wait_mbox = MI_SEMAPHORE_SYNC_RVE, .mbox_reg = GEN6_VERSYNC },
 				},
-				[VCS] = {
-					[RCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VR,  .mbox_reg = GEN6_RVSYNC },
-					[BCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VB,  .mbox_reg = GEN6_BVSYNC },
-					[VECS] = { .wait_mbox = MI_SEMAPHORE_SYNC_VVE, .mbox_reg = GEN6_VEVSYNC },
+				[VCS_HW] = {
+					[RCS_HW] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VR,  .mbox_reg = GEN6_RVSYNC },
+					[BCS_HW] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VB,  .mbox_reg = GEN6_BVSYNC },
+					[VECS_HW] = { .wait_mbox = MI_SEMAPHORE_SYNC_VVE, .mbox_reg = GEN6_VEVSYNC },
 				},
-				[BCS] = {
-					[RCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_BR,  .mbox_reg = GEN6_RBSYNC },
-					[VCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_BV,  .mbox_reg = GEN6_VBSYNC },
-					[VECS] = { .wait_mbox = MI_SEMAPHORE_SYNC_BVE, .mbox_reg = GEN6_VEBSYNC },
+				[BCS_HW] = {
+					[RCS_HW] =  { .wait_mbox = MI_SEMAPHORE_SYNC_BR,  .mbox_reg = GEN6_RBSYNC },
+					[VCS_HW] =  { .wait_mbox = MI_SEMAPHORE_SYNC_BV,  .mbox_reg = GEN6_VBSYNC },
+					[VECS_HW] = { .wait_mbox = MI_SEMAPHORE_SYNC_BVE, .mbox_reg = GEN6_VEBSYNC },
 				},
-				[VECS] = {
-					[RCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VER, .mbox_reg = GEN6_RVESYNC },
-					[VCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VEV, .mbox_reg = GEN6_VVESYNC },
-					[BCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VEB, .mbox_reg = GEN6_BVESYNC },
+				[VECS_HW] = {
+					[RCS_HW] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VER, .mbox_reg = GEN6_RVESYNC },
+					[VCS_HW] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VEV, .mbox_reg = GEN6_VVESYNC },
+					[BCS_HW] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VEB, .mbox_reg = GEN6_BVESYNC },
 				},
 			};
 			u32 wait_mbox;
 			i915_reg_t mbox_reg;
 
-			if (i == engine->id || i == VCS2) {
+			if (i == engine->hw_id) {
 				wait_mbox = MI_SEMAPHORE_SYNC_INVALID;
 				mbox_reg = GEN6_NOSYNC;
 			} else {
-				wait_mbox = sem_data[engine->id][i].wait_mbox;
-				mbox_reg = sem_data[engine->id][i].mbox_reg;
+				wait_mbox = sem_data[engine->hw_id][i].wait_mbox;
+				mbox_reg = sem_data[engine->hw_id][i].mbox_reg;
 			}
 
 			engine->semaphore.mbox.wait[i] = wait_mbox;

drivers/gpu/drm/i915/intel_ringbuffer.h

···
 		u32	sync_seqno[I915_NUM_ENGINES-1];
 
 		union {
+#define GEN6_SEMAPHORE_LAST	VECS_HW
+#define GEN6_NUM_SEMAPHORES	(GEN6_SEMAPHORE_LAST + 1)
+#define GEN6_SEMAPHORES_MASK	GENMASK(GEN6_SEMAPHORE_LAST, 0)
 			struct {
 				/* our mbox written by others */
-				u32		wait[I915_NUM_ENGINES];
+				u32		wait[GEN6_NUM_SEMAPHORES];
 				/* mboxes this ring signals to */
-				i915_reg_t	signal[I915_NUM_ENGINES];
+				i915_reg_t	signal[GEN6_NUM_SEMAPHORES];
 			} mbox;
 			u64		signal_ggtt[I915_NUM_ENGINES];
 		};