On 4/13/2022 12:27, Umesh Nerlige Ramappa wrote:
From: Tilak Tangudu <tilak.tangudu@xxxxxxxxx>
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
Is this comment accurate? I'm not seeing a 'wait for idle ack' in the
deltas. There is a wait for idle function but it is already present and
not part of this patch change.
Signed-off-by: Tilak Tangudu <tilak.tangudu@xxxxxxxxx>
---
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)
So the PSMI_GRANULARITY bit is not valid for Gen12 onwards? I'm not
actually seeing it being used anywhere. So I guess it doesn't matte anyway!
Reviewed-by: John Harrison <John.C.Harrison@xxxxxxxxx>
#define GFX_PPGTT_ENABLE (1 << 9)
#define GEN8_GFX_PPGTT_48B (1 << 7)
#define GFX_FORWARD_VBLANK_MASK (3 << 5)
