The Driver-FLR flow may inadvertently exit early before the full
completion of the re-init of the internal HW state if we only poll
GU_DEBUG Bit31 (polling for it to toggle from 0 -> 1). Instead
we need a two-step completion wait-for-completion flow that also
involves GU_CNTL. See the patch and new code comments for detail.
This is new direction from HW architecture folks.
Signed-off-by: Alan Previn <alan.previn.teres.alexis@xxxxxxxxx>
Fixes: 5a44fcd73498 ("drm/i915/gsc: Do a driver-FLR on unload if GSC was loaded")
---
drivers/gpu/drm/i915/intel_uncore.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 8dee9e62a73e..959869e2ff05 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -2748,6 +2748,12 @@ static void driver_initiated_flr(struct intel_uncore *uncore)
/* Trigger the actual Driver-FLR */
intel_uncore_rmw_fw(uncore, GU_CNTL, 0, DRIVERFLR);
+ /* Completion Step 1 - poll for 'CNTL-BIT31 = 0' wait for hw teardown to complete */
+ ret = intel_wait_for_register_fw(uncore, GU_CNTL,
+ DRIVERFLR_STATUS, 0,
+ flr_timeout_ms);
+
+ /* Completion: Step 2 - poll for 'DEBUG-BIT31 = 1' for hw/fw re-init to complete */
ret = intel_wait_for_register_fw(uncore, GU_DEBUG,
DRIVERFLR_STATUS, DRIVERFLR_STATUS,
flr_timeout_ms);
@@ -2756,6 +2762,7 @@ static void driver_initiated_flr(struct intel_uncore *uncore)
return;
}
+ /* Write 1 to clear GU_DEBUG's sticky completion status bit */
intel_uncore_write_fw(uncore, GU_DEBUG, DRIVERFLR_STATUS);
}
base-commit: 0a0ee61784df01ac098a92bd43673ee30c629f13
--
2.39.0
