drm/i915: Add the gen12_needs_ccs_aux_inv helper

We always assumed that a device might either have AUX or FLAT
CCS, but this is an approximation that is not always true, e.g.
PVC represents an exception.

Set the basis for future finer selection by implementing a
boolean gen12_needs_ccs_aux_inv() function that tells whether aux
invalidation is needed or not.

Currently PVC is the only exception to the above mentioned rule.

Requires: 059ae7ae2a1c ("drm/i915/gt: Cleanup aux invalidation registers")
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Jonathan Cavitt <jonathan.cavitt@intel.com>
Cc: <stable@vger.kernel.org> # v5.8+
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230725001950.1014671-3-andi.shyti@linux.intel.com

drivers/gpu/drm/i915/gt/gen8_engine_cs.c

@@ -165,6 +165,18 @@ static u32 preparser_disable(bool state)
 	return MI_ARB_CHECK | 1 << 8 | state;
 }
 
+static bool gen12_needs_ccs_aux_inv(struct intel_engine_cs *engine)
+{
+	if (IS_PONTEVECCHIO(engine->i915))
+		return false;
+
+	/*
+	 * so far platforms supported by i915 having
+	 * flat ccs do not require AUX invalidation
+	 */
+	return !HAS_FLAT_CCS(engine->i915);
+}
+
 u32 *gen12_emit_aux_table_inv(struct intel_gt *gt, u32 *cs, const i915_reg_t inv_reg)
 {
 	u32 gsi_offset = gt->uncore->gsi_offset;
@@ -267,7 +279,7 @@ int gen12_emit_flush_rcs(struct i915_request *rq, u32 mode)
 		else if (engine->class == COMPUTE_CLASS)
 			flags &= ~PIPE_CONTROL_3D_ENGINE_FLAGS;
 
-		if (!HAS_FLAT_CCS(rq->i915))
+		if (gen12_needs_ccs_aux_inv(rq->engine))
 			count = 8 + 4;
 		else
 			count = 8;
@@ -285,7 +297,7 @@ int gen12_emit_flush_rcs(struct i915_request *rq, u32 mode)
 
 		cs = gen8_emit_pipe_control(cs, flags, LRC_PPHWSP_SCRATCH_ADDR);
 
-		if (!HAS_FLAT_CCS(rq->i915)) {
+		if (gen12_needs_ccs_aux_inv(rq->engine)) {
 			/* hsdes: 1809175790 */
 			cs = gen12_emit_aux_table_inv(rq->engine->gt, cs,
 						      GEN12_CCS_AUX_INV);
@@ -307,7 +319,7 @@ int gen12_emit_flush_xcs(struct i915_request *rq, u32 mode)
 	if (mode & EMIT_INVALIDATE) {
 		cmd += 2;
 
-		if (!HAS_FLAT_CCS(rq->i915) &&
+		if (gen12_needs_ccs_aux_inv(rq->engine) &&
 		    (rq->engine->class == VIDEO_DECODE_CLASS ||
 		     rq->engine->class == VIDEO_ENHANCEMENT_CLASS)) {
 			aux_inv = rq->engine->mask &