On 10/16/2023 15:55, Vinay Belgaumkar wrote:
This bit does not cause an explicit L3 flush. We already use
At all? Or only on newer hardware? And as a genuine spec change or as a bug / workaround?

If the hardware has re-purposed the bit then it is probably worth at least adding a comment to the bit definition to say that it is only valid up to IP version 12.70.

PIPE_CONTROL_DC_FLUSH_ENABLE for that purpose.

Cc: Nirmoy Das <nirmoy....@intel.com>
Cc: Mikka Kuoppala <mika.kuopp...@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaum...@intel.com>
---
  drivers/gpu/drm/i915/gt/gen8_engine_cs.c | 8 ++++++--
  1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c 
b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
index ba4c2422b340..abbc02f3e66e 100644
--- a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
@@ -247,6 +247,7 @@ static int mtl_dummy_pipe_control(struct i915_request *rq)
  int gen12_emit_flush_rcs(struct i915_request *rq, u32 mode)
  {
        struct intel_engine_cs *engine = rq->engine;
+       struct intel_gt *gt = rq->engine->gt;
/*
         * On Aux CCS platforms the invalidation of the Aux
@@ -278,7 +279,8 @@ int gen12_emit_flush_rcs(struct i915_request *rq, u32 mode)
                 * deals with Protected Memory which is not needed for
                 * AUX CCS invalidation and lead to unwanted side effects.
                 */
-               if (mode & EMIT_FLUSH)
+               if ((mode & EMIT_FLUSH) &&
+                   !(IS_GFX_GT_IP_RANGE(gt, IP_VER(12, 70), IP_VER(12, 71))))
Why stop at 12.71? Is the meaning only changed for 12.70 and the old/correct version will be restored in later hardware?

John.


                        bit_group_1 |= PIPE_CONTROL_FLUSH_L3;
bit_group_1 |= PIPE_CONTROL_TILE_CACHE_FLUSH;
@@ -812,12 +814,14 @@ u32 *gen12_emit_fini_breadcrumb_rcs(struct i915_request 
*rq, u32 *cs)
        u32 flags = (PIPE_CONTROL_CS_STALL |
                     PIPE_CONTROL_TLB_INVALIDATE |
                     PIPE_CONTROL_TILE_CACHE_FLUSH |
-                    PIPE_CONTROL_FLUSH_L3 |
                     PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH |
                     PIPE_CONTROL_DEPTH_CACHE_FLUSH |
                     PIPE_CONTROL_DC_FLUSH_ENABLE |
                     PIPE_CONTROL_FLUSH_ENABLE);
+ if (!(IS_GFX_GT_IP_RANGE(gt, IP_VER(12, 70), IP_VER(12, 71))))
+               flags |= PIPE_CONTROL_FLUSH_L3;
+
        /* Wa_14016712196 */
        if (IS_GFX_GT_IP_RANGE(gt, IP_VER(12, 70), IP_VER(12, 71)) || 
IS_DG2(i915))
                /* dummy PIPE_CONTROL + depth flush */

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