[PATCH v6 2/3] drm/i915/gt: Do not generate the command streamer for all the CCS

[Andi Shyti <andi.shyti@linux.intel.com>]

We want a fixed load CCS balancing consisting in all slices
sharing one single user engine. For this reason do not create the
intel_engine_cs structure with its dedicated command streamer for
CCS slices beyond the first.

Fixes: d2eae8e98d59 ("drm/i915/dg2: Drop force_probe requirement")
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Chris Wilson <chris.p.wilson@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: <stable@vger.kernel.org> # v6.2+
---
 drivers/gpu/drm/i915/gt/intel_engine_cs.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index f553cf4e6449..c4fb31bb6e72 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -966,6 +966,7 @@ int intel_engines_init_mmio(struct intel_gt *gt)
 	const unsigned int engine_mask = init_engine_mask(gt);
 	unsigned int mask = 0;
 	unsigned int i, class;
+	u8 ccs_instance = 0;
 	u8 logical_ids[MAX_ENGINE_INSTANCE + 1];
 	int err;
 
@@ -986,6 +987,19 @@ int intel_engines_init_mmio(struct intel_gt *gt)
 			    !HAS_ENGINE(gt, i))
 				continue;
 
+			/*
+			 * Do not create the command streamer for CCS slices
+			 * beyond the first. All the workload submitted to the
+			 * first engine will be shared among all the slices.
+			 *
+			 * Once the user will be allowed to customize the CCS
+			 * mode, then this check needs to be removed.
+			 */
+			if (IS_DG2(i915) &&
+			    class == COMPUTE_CLASS &&
+			    ccs_instance++)
+				continue;
+
 			err = intel_engine_setup(gt, i,
 						 logical_ids[instance]);
 			if (err)
@@ -996,11 +1010,9 @@ int intel_engines_init_mmio(struct intel_gt *gt)
 	}
 
 	/*
-	 * Catch failures to update intel_engines table when the new engines
-	 * are added to the driver by a warning and disabling the forgotten
-	 * engines.
+	 * Update the intel_engines table.
 	 */
-	if (drm_WARN_ON(&i915->drm, mask != engine_mask))
+	if (mask != engine_mask)
 		gt->info.engine_mask = mask;
 
 	gt->info.num_engines = hweight32(mask);
-- 
2.43.0