[PATCH v1 11/14] drm/i915/gt: Store active CCS mask

[Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>]

To support upcoming patches, we need to store the current mask
for active CCS engines.

Active engines refer to those exposed to userspace via the UABI
engine list.

Signed-off-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c | 54 ++++++++++++++++-----
 drivers/gpu/drm/i915/gt/intel_gt_types.h    |  7 +++
 2 files changed, 49 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c b/drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c
index ed3ad881a89d..45e9280f9bac 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c
@@ -12,9 +12,10 @@
 static void intel_gt_apply_ccs_mode(struct intel_gt *gt)
 {
 	unsigned long cslices_mask = CCS_MASK(gt);
-	u32 mode_val = 0;
+	unsigned long ccs_mask = gt->ccs.id_mask;
 	/* CCS mode, i.e. number of CCS engines to be enabled */
-	u32 width = 1;
+	u32 width = hweight32(ccs_mask);
+	u32 mode_val = 0;
 	/* CCS engine id, i.e. the engines position in the engine's bitmask */
 	int engine;
 	int cslice;
@@ -57,7 +58,7 @@ static void intel_gt_apply_ccs_mode(struct intel_gt *gt)
 	 *   slice 2: ccs2
 	 *   slice 3: ccs3
 	 */
-	engine = __ffs(cslices_mask);
+	engine = __ffs(ccs_mask);
 
 	for (cslice = 0; cslice < I915_MAX_CCS; cslice++) {
 		if (!(cslices_mask & BIT(cslice))) {
@@ -73,29 +74,58 @@ static void intel_gt_apply_ccs_mode(struct intel_gt *gt)
 		mode_val |= XEHP_CCS_MODE_CSLICE(cslice, engine);
 
 		if (!width) {
-			/*
-			 * CCS mode, will be used later to
-			 * reset to a flexible value
-			 */
-			width = 1;
-			engine = __ffs(cslices_mask);
+			/* CCS mode, reset to the initial mode */
+			width = hweight32(ccs_mask);
+			engine = __ffs(ccs_mask);
 			continue;
 		}
 
 		width--;
-		engine = find_next_bit(&cslices_mask, I915_MAX_CCS, engine + 1);
+		engine = find_next_bit(&ccs_mask, I915_MAX_CCS, engine + 1);
 	}
 
 	gt->ccs.mode_reg_val = mode_val;
 }
 
+static void __update_ccs_mask(struct intel_gt *gt, u32 ccs_mode)
+{
+	unsigned long cslices_mask = CCS_MASK(gt);
+	int i;
+
+	/* Mask off all the CCS engines */
+	gt->ccs.id_mask = 0;
+
+	for_each_set_bit(i, &cslices_mask, I915_MAX_CCS) {
+		gt->ccs.id_mask |= BIT(i);
+
+		ccs_mode--;
+		if (!ccs_mode)
+			break;
+	}
+
+	/*
+	 * It's impossible for 'ccs_mode' to be zero at this point.
+	 * This scenario would only occur if the 'ccs_mode' provided by
+	 * the caller exceeded the total number of CCS engines, a condition
+	 * we check before calling the 'update_ccs_mask()' function.
+	 */
+	GEM_BUG_ON(ccs_mode);
+
+	/* Initialize the CCS mode setting */
+	intel_gt_apply_ccs_mode(gt);
+}
+
 void intel_gt_ccs_mode_init(struct intel_gt *gt)
 {
 	if (!IS_DG2(gt->i915))
 		return;
 
-	/* Initialize the CCS mode setting */
-	intel_gt_apply_ccs_mode(gt);
+	/*
+	 * Set CCS balance mode 1 in the ccs_mask.
+	 *
+	 * During init the workaround are not set up yet.
+	 */
+	__update_ccs_mask(gt, 1);
 }
 
 static ssize_t num_cslices_show(struct device *dev,
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_types.h b/drivers/gpu/drm/i915/gt/intel_gt_types.h
index 71e43071da0b..641be69016e1 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_types.h
@@ -219,6 +219,13 @@ struct intel_gt {
 	 */
 	struct {
 		u32 mode_reg_val;
+
+		/*
+		 * CCS id_mask is the command streamer instance
+		 * exposed to the user. While the CCS_MASK(gt)
+		 * is the available unfused compute slices.
+		 */
+		intel_engine_mask_t id_mask;
 	} ccs;
 
 	/*
-- 
2.45.2