drm/xe: Enable Fixed CCS mode setting

Disable dynamic HW load balancing of compute resource assignment
to engines and instead enabled fixed mode of mapping compute
resources to engines on all platforms with more than one compute
engine.

By default enable only one CCS engine with all compute slices
assigned to it. This is the desired configuration for common
workloads.

PVC platform supports only the fixed CCS mode (workaround 16016805146).

v2: Rebase, make it platform agnostic
v3: Minor code refactoring

Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
new file mode 100644
index 000000000000..541c44c70a84
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#include "regs/xe_gt_regs.h"
+#include "xe_assert.h"
+#include "xe_gt.h"
+#include "xe_gt_ccs_mode.h"
+#include "xe_mmio.h"
+
+static void __xe_gt_apply_ccs_mode(struct xe_gt *gt, u32 num_engines)
+{
+	u32 mode = CCS_MODE_CSLICE_0_3_MASK; /* disable all by default */
+	int num_slices = hweight32(CCS_MASK(gt));
+	struct xe_device *xe = gt_to_xe(gt);
+	int width, cslice = 0;
+	u32 config = 0;
+
+	xe_assert(xe, xe_gt_ccs_mode_enabled(gt));
+
+	xe_assert(xe, num_engines && num_engines <= num_slices);
+	xe_assert(xe, !(num_slices % num_engines));
+
+	/*
+	 * Loop over all available slices and assign each a user engine.
+	 * For example, if there are four compute slices available, the
+	 * assignment of compute slices to compute engines would be,
+	 *
+	 * With 1 engine (ccs0):
+	 *   slice 0, 1, 2, 3: ccs0
+	 *
+	 * With 2 engines (ccs0, ccs1):
+	 *   slice 0, 2: ccs0
+	 *   slice 1, 3: ccs1
+	 *
+	 * With 4 engines (ccs0, ccs1, ccs2, ccs3):
+	 *   slice 0: ccs0
+	 *   slice 1: ccs1
+	 *   slice 2: ccs2
+	 *   slice 3: ccs3
+	 */
+	for (width = num_slices / num_engines; width; width--) {
+		struct xe_hw_engine *hwe;
+		enum xe_hw_engine_id id;
+
+		for_each_hw_engine(hwe, gt, id) {
+			if (hwe->class != XE_ENGINE_CLASS_COMPUTE)
+				continue;
+
+			if (hwe->logical_instance >= num_engines)
+				break;
+
+			config |= BIT(hwe->instance) << XE_HW_ENGINE_CCS0;
+
+			/* If a slice is fused off, leave disabled */
+			while ((CCS_MASK(gt) & BIT(cslice)) == 0)
+				cslice++;
+
+			mode &= ~CCS_MODE_CSLICE(cslice, CCS_MODE_CSLICE_MASK);
+			mode |= CCS_MODE_CSLICE(cslice, hwe->instance);
+			cslice++;
+		}
+	}
+
+	xe_mmio_write32(gt, CCS_MODE, mode);
+
+	xe_gt_info(gt, "CCS_MODE=%x config:%08x, num_engines:%d, num_slices:%d\n",
+		   mode, config, num_engines, num_slices);
+}
+
+void xe_gt_apply_ccs_mode(struct xe_gt *gt)
+{
+	if (!gt->ccs_mode)
+		return;
+
+	__xe_gt_apply_ccs_mode(gt, gt->ccs_mode);
+}