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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2017-10-27 10:43:11 +0100 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2017-10-27 12:09:29 +0100 |
| commit | 11caf5517c2c9eebd435c60e9343a3784d74e9a1 (patch) | |
| tree | 2528a96186675d35d2a3fdba9f5195beb18a44c0 /drivers/gpu/drm/i915/intel_uncore.c | |
| parent | e6ed2a1b99051bc04abcc2daed3972efada0b7a9 (diff) | |
| download | op-kernel-dev-11caf5517c2c9eebd435c60e9343a3784d74e9a1.zip op-kernel-dev-11caf5517c2c9eebd435c60e9343a3784d74e9a1.tar.gz | |
drm/i915: Empty the ring before disabling
An interesting snippet from Sandybridge's prm:
"Although a Ring Buffer can be enabled in the non-empty state, it must
not be disabled unless it is empty. Attempting to disable a Ring Buffer
in the non-empty state is UNDEFINED."
Let's avoid the undefined behaviour as we disable the rings prior to
reset and resume.
v2: Tell HEAD to catch up to TAIL (empty ring) first, then reset both to
0 (supposedly while stopped).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027094311.30380-1-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/intel_uncore.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_uncore.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index 20e3c65c..96ee6b2 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -1387,10 +1387,14 @@ static void gen3_stop_engine(struct intel_engine_cs *engine) DRM_DEBUG_DRIVER("%s: timed out on STOP_RING\n", engine->name); - I915_WRITE_FW(RING_CTL(base), 0); + I915_WRITE_FW(RING_HEAD(base), I915_READ_FW(RING_TAIL(base))); + I915_WRITE_FW(RING_HEAD(base), 0); I915_WRITE_FW(RING_TAIL(base), 0); + /* The ring must be empty before it is disabled */ + I915_WRITE_FW(RING_CTL(base), 0); + /* Check acts as a post */ if (I915_READ_FW(RING_HEAD(base)) != 0) DRM_DEBUG_DRIVER("%s: ring head not parked\n", |
