drm/i915/cnl: WaPushConstantDereferenceHoldDisable

CS sometimes hangs on 3D Push Constant dispatches with the new
deref enhancement logic in CNL.

v2: Improve the commit message (Rodrigo)

Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1503518191-19116-1-git-send-email-oscar.mateo@intel.com

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index d23f18874309..d7e1ccf778a2 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1083,6 +1083,9 @@ static int cnl_init_workarounds(struct intel_engine_cs *engine)
         WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
                    GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
 
+        /* WaPushConstantDereferenceHoldDisable:cnl */
+        WA_SET_BIT(GEN7_ROW_CHICKEN2, PUSH_CONSTANT_DEREF_DISABLE);
+
         /* WaEnablePreemptionGranularityControlByUMD:cnl */
         ret= wa_ring_whitelist_reg(engine, GEN8_CS_CHICKEN1);
         if (ret)