[Intel-gfx] [PATCH v3] drm/i915/gen11: enable support for headerless msgs

[Dongwon Kim]

Setting bit5 (headerless msg for preemptable GPGPU context) of SAMPLER_MODE
register to enable support for the headless msgs on gen11. None of existing
use cases will be affected by this as this change makes both types of message
- headerless and w/ header supported at the same time. It also complies with
the new recommendation for the default bit value for the next gen.

v2: rewrote commit message to include more information
v3: setting the bit in icl_ctx_workarounds_init()

Signed-off-by: Dongwon Kim <dongwon.kim at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h          | 1 +
 drivers/gpu/drm/i915/intel_workarounds.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index b74824f0b5b1..b45042f71c0a 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -8862,6 +8862,7 @@ enum {
 #define   GEN11_LSN_UNSLCVC_GAFS_HALF_SF_MAXALLOC	(1 << 7)
 
 #define GEN10_SAMPLER_MODE		_MMIO(0xE18C)
+#define   GEN11_SAMPLER_ENABLE_HEADLESS_MSG	(1 << 5)
 
 /* IVYBRIDGE DPF */
 #define GEN7_L3CDERRST1(slice)		_MMIO(0xB008 + (slice) * 0x200) /* L3CD Error Status 1 */
diff --git a/drivers/gpu/drm/i915/intel_workarounds.c b/drivers/gpu/drm/i915/intel_workarounds.c
index b3cbed1ee1c9..58ddb60772b3 100644
--- a/drivers/gpu/drm/i915/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/intel_workarounds.c
@@ -575,6 +575,10 @@ static void icl_ctx_workarounds_init(struct intel_engine_cs *engine)
 	WA_SET_FIELD_MASKED(GEN8_CS_CHICKEN1,
 			    GEN9_PREEMPT_GPGPU_LEVEL_MASK,
 			    GEN9_PREEMPT_GPGPU_THREAD_GROUP_LEVEL);
+
+	/* allow headerless messages for preemptable GPGPU context */
+	WA_SET_BIT_MASKED(GEN10_SAMPLER_MODE,
+			  GEN11_SAMPLER_ENABLE_HEADLESS_MSG);
 }
 
 void intel_engine_init_ctx_wa(struct intel_engine_cs *engine)
-- 
2.17.1