[Intel-gfx] [PATCH 06/10] drm/i915: Add Wa_22011802037 force cs halt

[Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>]

From: Tilak Tangudu <tilak.tangudu@intel.com>

Prior to doing a reset, SW must ensure command streamer is stopped,
as a workaround, to eliminate a race condition in GPM flow.
Setting both the ring stop and prefetch disable bits, will cause the
command streamer to halt.

v2: 1. Removed duplicate code and added only prefetch disable -Chris Wilson

v3: 1. Applied wa for all gen12+ -Lahtinen Joonas/Vivi Rodrigo

v4: 1. Added description in comment
    2. Added WA prior to read barrier-Chris Wilson

v5: 1. Modified to disable prefetch and wait for idle ack -Chris Wilson

Signed-off-by: Tilak Tangudu <tilak.tangudu@intel.com>
---
 drivers/gpu/drm/i915/gt/intel_engine_cs.c   | 9 +++++++++
 drivers/gpu/drm/i915/gt/intel_engine_regs.h | 1 +
 2 files changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 98b61ff13c95..14c6ddbbfde8 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -1280,6 +1280,15 @@ static int __intel_engine_stop_cs(struct intel_engine_cs *engine,
 	int err;
 
 	intel_uncore_write_fw(uncore, mode, _MASKED_BIT_ENABLE(STOP_RING));
+
+	/*
+	 * Wa_22011802037 : gen12, Prior to doing a reset, ensure CS is
+	 * stopped, set ring stop bit and prefetch disable bit to halt CS
+	 */
+	if (GRAPHICS_VER(engine->i915) == 12)
+		intel_uncore_write_fw(uncore, RING_MODE_GEN7(engine->mmio_base),
+				      _MASKED_BIT_ENABLE(GEN12_GFX_PREFETCH_DISABLE));
+
 	err = __intel_wait_for_register_fw(engine->uncore, mode,
 					   MODE_IDLE, MODE_IDLE,
 					   fast_timeout_us,
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_regs.h b/drivers/gpu/drm/i915/gt/intel_engine_regs.h
index 0bf8b45c9319..594a629cb28f 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_regs.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_regs.h
@@ -181,6 +181,7 @@
 #define   GFX_SURFACE_FAULT_ENABLE		(1 << 12)
 #define   GFX_REPLAY_MODE			(1 << 11)
 #define   GFX_PSMI_GRANULARITY			(1 << 10)
+#define   GEN12_GFX_PREFETCH_DISABLE		REG_BIT(10)
 #define   GFX_PPGTT_ENABLE			(1 << 9)
 #define   GEN8_GFX_PPGTT_48B			(1 << 7)
 #define   GFX_FORWARD_VBLANK_MASK		(3 << 5)
-- 
2.35.1