[Intel-gfx] [PATCH] 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

Signed-off-by: Dongwon Kim <dongwon.kim at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h  |  1 +
 drivers/gpu/drm/i915/intel_lrc.c | 18 ++++++++++++++++++
 2 files changed, 19 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_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 4e0a351bfbca..07c8fe2a5549 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1807,6 +1807,21 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
 	return 0;
 }
 
+static int gen11_init_render_ring(struct intel_engine_cs *engine)
+{
+	struct drm_i915_private *dev_priv = engine->i915;
+	int ret;
+
+	ret = gen8_init_common_ring(engine);
+	if (ret)
+		return ret;
+
+	/* allow headerless messages for pre-emptable GPGPU contexts */
+	I915_WRITE(GEN10_SAMPLER_MODE, _MASKED_BIT_ENABLE(GEN11_SAMPLER_ENABLE_HEADLESS_MSG));
+
+	return 0;
+}
+
 static void execlists_reset_prepare(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
@@ -2516,6 +2531,9 @@ int logical_render_ring_init(struct intel_engine_cs *engine)
 		return ret;
 
 	/* Override some for render ring. */
+	if (INTEL_GEN(engine->i915) == 11)
+		engine->init_hw = gen11_init_render_ring;
+
 	engine->init_context = gen8_init_rcs_context;
 	engine->emit_flush = gen8_emit_flush_render;
 	engine->emit_fini_breadcrumb = gen8_emit_fini_breadcrumb_rcs;
-- 
2.17.1