[PATCH 08/13] drm/i915/lrc: Skip no-op per-bb buffer on gen9

[Chris Wilson]

Since we inherited the context image setup from gen8 which needed a
per-bb workaround (for GPGPU), we are submitting an empty per-bb buffer
on gen9. Now that we can skip adding the buffer to the context image,
remove the dangling per-bb. This slightly improves execution latency,
most notably on an idle engine.

References: https://bugs.freedesktop.org/show_bug.cgi?id=87725
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 8d158deda328..3623403a4f2d 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1184,13 +1184,6 @@ static u32 *gen9_init_indirectctx_bb(struct intel_engine_cs *engine, u32 *batch)
 	return batch;
 }
 
-static u32 *gen9_init_perctx_bb(struct intel_engine_cs *engine, u32 *batch)
-{
-	*batch++ = MI_BATCH_BUFFER_END;
-
-	return batch;
-}
-
 #define CTX_WA_BB_OBJ_SIZE (PAGE_SIZE)
 
 static int lrc_setup_wa_ctx(struct intel_engine_cs *engine)
@@ -1247,7 +1240,7 @@ static int intel_init_workaround_bb(struct intel_engine_cs *engine)
 		return 0;
 	case 9:
 		wa_bb_fn[0] = gen9_init_indirectctx_bb;
-		wa_bb_fn[1] = gen9_init_perctx_bb;
+		wa_bb_fn[1] = NULL;
 		break;
 	case 8:
 		wa_bb_fn[0] = gen8_init_indirectctx_bb;
-- 
2.14.1