drm/i915/xehp: Support platforms with CCS engines but no RCS

In the past we've always assumed that an RCS engine is present on every
platform.  However now that we have compute engines there may be
platforms that have CCS engines but no RCS, or platforms that are
designed to have both, but have the RCS engine fused off.

Various engine-centric initialization that only needs to be done a
single time for the group of RCS+CCS engines can't rely on being setup
with the RCS now; instead we add a I915_ENGINE_FIRST_RENDER_COMPUTE flag
that will be assigned to a single engine in the group; whichever engine
has this flag will be responsible for some of the general setup
(RCU_MODE programming, initialization of certain workarounds, etc.).

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220303223435.2793124-1-matthew.d.roper@intel.com

drivers/gpu/drm/i915/gt/intel_engine_cs.c

@@ -434,6 +434,11 @@ static int intel_engine_setup(struct intel_gt *gt, enum intel_engine_id id,
 	if (GRAPHICS_VER(i915) == 12 && engine->class == RENDER_CLASS)
 		engine->props.preempt_timeout_ms = 0;
 
+	if ((engine->class == COMPUTE_CLASS && !RCS_MASK(engine->gt) &&
+	     __ffs(CCS_MASK(engine->gt)) == engine->instance) ||
+	     engine->class == RENDER_CLASS)
+		engine->flags |= I915_ENGINE_FIRST_RENDER_COMPUTE;
+
 	/* features common between engines sharing EUs */
 	if (engine->class == RENDER_CLASS || engine->class == COMPUTE_CLASS) {
 		engine->flags |= I915_ENGINE_HAS_RCS_REG_STATE;

drivers/gpu/drm/i915/gt/intel_engine_types.h

@@ -97,6 +97,7 @@ struct i915_ctx_workarounds {
 #define I915_MAX_VCS	8
 #define I915_MAX_VECS	4
 #define I915_MAX_CCS	4
+#define I915_MAX_RCS	1
 
 /*
  * Engine IDs definitions.
@@ -526,6 +527,7 @@ struct intel_engine_cs {
 #define I915_ENGINE_WANT_FORCED_PREEMPTION BIT(8)
 #define I915_ENGINE_HAS_RCS_REG_STATE  BIT(9)
 #define I915_ENGINE_HAS_EU_PRIORITY    BIT(10)
+#define I915_ENGINE_FIRST_RENDER_COMPUTE BIT(11)
 	unsigned int flags;
 
 	/*

drivers/gpu/drm/i915/gt/intel_execlists_submission.c

@@ -2911,7 +2911,7 @@ static int execlists_resume(struct intel_engine_cs *engine)
 
 	enable_execlists(engine);
 
-	if (engine->class == RENDER_CLASS)
+	if (engine->flags & I915_ENGINE_FIRST_RENDER_COMPUTE)
 		xehp_enable_ccs_engines(engine);
 
 	return 0;

drivers/gpu/drm/i915/gt/intel_workarounds.c

@@ -2633,7 +2633,7 @@ engine_init_workarounds(struct intel_engine_cs *engine, struct i915_wa_list *wal
 	 * to a single RCS/CCS engine's workaround list since
 	 * they're reset as part of the general render domain reset.
 	 */
-	if (engine->class == RENDER_CLASS)
+	if (engine->flags & I915_ENGINE_FIRST_RENDER_COMPUTE)
 		general_render_compute_wa_init(engine, wal);
 
 	if (engine->class == RENDER_CLASS)

drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c

@@ -335,7 +335,7 @@ static int guc_mmio_regset_init(struct temp_regset *regset,
 	ret |= GUC_MMIO_REG_ADD(regset, RING_HWS_PGA(base), false);
 	ret |= GUC_MMIO_REG_ADD(regset, RING_IMR(base), false);
 
-	if (engine->class == RENDER_CLASS &&
+	if ((engine->flags & I915_ENGINE_FIRST_RENDER_COMPUTE) &&
 	    CCS_MASK(engine->gt))
 		ret |= GUC_MMIO_REG_ADD(regset, GEN12_RCU_MODE, true);
 

drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c

@@ -3616,7 +3616,7 @@ static int guc_resume(struct intel_engine_cs *engine)
 	setup_hwsp(engine);
 	start_engine(engine);
 
-	if (engine->class == RENDER_CLASS)
+	if (engine->flags & I915_ENGINE_FIRST_RENDER_COMPUTE)
 		xehp_enable_ccs_engines(engine);
 
 	return 0;

drivers/gpu/drm/i915/i915_drv.h

@@ -1237,6 +1237,8 @@ IS_SUBPLATFORM(const struct drm_i915_private *i915,
 	((gt)->info.engine_mask &						\
 	 GENMASK(first__ + count__ - 1, first__)) >> first__;		\
 })
+#define RCS_MASK(gt) \
+	ENGINE_INSTANCES_MASK(gt, RCS0, I915_MAX_RCS)
 #define VDBOX_MASK(gt) \
 	ENGINE_INSTANCES_MASK(gt, VCS0, I915_MAX_VCS)
 #define VEBOX_MASK(gt) \