[PATCH 1/2] drm/i915/gt: Disable HW load balancing for CCS

Andi Shyti
2024-02-20T14:21:08Z

The hardware should not dynamically balance the load between CCS
engines. Wa_16016805146 recommends disabling it across all
platforms.

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_gt_regs.h | 1 +
drivers/gpu/drm/i915/gt/intel_workarounds.c | 6 ++++++
2 files changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_regs.h b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
index 50962cfd1353..cf709f6c05ae 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_regs.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
@@ -1478,6 +1478,7 @@

#define GEN12_RCU_MODE _MMIO(0x14800)
#define GEN12_RCU_MODE_CCS_ENABLE REG_BIT(0)
+#define XEHP_RCU_MODE_FIXED_SLICE_CCS_MODE REG_BIT(1)

#define CHV_FUSE_GT _MMIO(VLV_GUNIT_BASE + 0x2168)
#define CHV_FGT_DISABLE_SS0 (1 << 10)
diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index d67d44611c28..7f42c8015f71 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -2988,6 +2988,12 @@ general_render_compute_wa_init(struct intel_engine_cs *engine, struct i915_wa_li
wa_mcr_masked_en(wal, GEN8_HALF_SLICE_CHICKEN1,
GEN7_PSD_SINGLE_PORT_DISPATCH_ENABLE);
}
+
+ /*
+ * Wa_16016805146: disable the CCS load balancing
+ * indiscriminately for all the platforms
+ */
+ wa_masked_en(wal, GEN12_RCU_MODE, XEHP_RCU_MODE_FIXED_SLICE_CCS_MODE);
}

static void
--
2.43.0