Re: [Intel-gfx] [PATCH V5] drm/i915/gt: Add workaround 14016712196

[Andrzej Hajda]

On 01.06.2023 13:09, Tejas Upadhyay wrote:

For mtl, workaround suggests that, SW insert a
dummy PIPE_CONTROL prior to PIPE_CONTROL which
contains a post sync: Timestamp or Write Immediate.

Bspec: 72197

V5:
   - Remove ret variable - Andi
V4:
   - Update commit message, avoid returing cs - Andi/Matt
V3:
   - Wrap dummy pipe control stuff in API - Andi
V2:
   - Fix  kernel test robot warnings

Closes: 
https://lore.kernel.org/oe-kbuild-all/202305121525.3ewdgoby-...@intel.com/
Reviewed-by: Andi Shyti <andi.sh...@linux.intel.com>
Signed-off-by: Tejas Upadhyay <tejas.upadh...@intel.com>

Reviewed-by: Andrzej Hajda <andrzej.ha...@intel.com>

Regards
Andrzej

---
  drivers/gpu/drm/i915/gt/gen8_engine_cs.c | 38 ++++++++++++++++++++++++
  1 file changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c 
b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
index e1c76e5bfa82..23857cc08eca 100644
--- a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
@@ -177,14 +177,40 @@ u32 *gen12_emit_aux_table_inv(struct intel_gt *gt, u32 
*cs, const i915_reg_t inv
        return cs;
  }

+static int mtl_dummy_pipe_control(struct i915_request *rq)

+{
+       /* Wa_14016712196 */
+       if (IS_MTL_GRAPHICS_STEP(rq->engine->i915, M, STEP_A0, STEP_B0) ||
+           IS_MTL_GRAPHICS_STEP(rq->engine->i915, P, STEP_A0, STEP_B0)) {
+               u32 *cs;
+
+               /* dummy PIPE_CONTROL + depth flush */
+               cs = intel_ring_begin(rq, 6);
+               if (IS_ERR(cs))
+                       return PTR_ERR(cs);
+               cs = gen12_emit_pipe_control(cs,
+                                            0,
+                                            PIPE_CONTROL_DEPTH_CACHE_FLUSH,
+                                            LRC_PPHWSP_SCRATCH_ADDR);
+               intel_ring_advance(rq, cs);
+       }
+
+       return 0;
+}
+
  int gen12_emit_flush_rcs(struct i915_request *rq, u32 mode)
  {
        struct intel_engine_cs *engine = rq->engine;

if (mode & EMIT_FLUSH) {

                u32 flags = 0;
+               int err;
                u32 *cs;

+ err = mtl_dummy_pipe_control(rq);

+               if (err)
+                       return err;
+
                flags |= PIPE_CONTROL_TILE_CACHE_FLUSH;
                flags |= PIPE_CONTROL_FLUSH_L3;
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
@@ -217,6 +243,11 @@ int gen12_emit_flush_rcs(struct i915_request *rq, u32 mode)
        if (mode & EMIT_INVALIDATE) {
                u32 flags = 0;
                u32 *cs, count;
+               int err;
+
+               err = mtl_dummy_pipe_control(rq);
+               if (err)
+                       return err;

flags |= PIPE_CONTROL_COMMAND_CACHE_INVALIDATE;

                flags |= PIPE_CONTROL_TLB_INVALIDATE;
@@ -733,6 +764,13 @@ u32 *gen12_emit_fini_breadcrumb_rcs(struct i915_request 
*rq, u32 *cs)
                     PIPE_CONTROL_DC_FLUSH_ENABLE |
                     PIPE_CONTROL_FLUSH_ENABLE);

+ /* Wa_14016712196 */

+       if (IS_MTL_GRAPHICS_STEP(i915, M, STEP_A0, STEP_B0) ||
+           IS_MTL_GRAPHICS_STEP(i915, P, STEP_A0, STEP_B0))
+               /* dummy PIPE_CONTROL + depth flush */
+               cs = gen12_emit_pipe_control(cs, 0,
+                                            PIPE_CONTROL_DEPTH_CACHE_FLUSH, 0);
+
        if (GRAPHICS_VER(i915) == 12 && GRAPHICS_VER_FULL(i915) < IP_VER(12, 
50))
                /* Wa_1409600907 */
                flags |= PIPE_CONTROL_DEPTH_STALL;