diff options
author | Michel Thierry <michel.thierry@intel.com> | 2015-04-15 19:11:33 +0200 |
---|---|---|
committer | Jani Nikula <jani.nikula@intel.com> | 2015-04-23 22:56:52 +0200 |
commit | 53292cdb066950611e5bc2e0eb109c7edb42af78 (patch) | |
tree | 2c2b0ed161701386dfff4000b084d9289c8eca97 | |
parent | drm/i915: cope with large i2c transfers (diff) | |
download | linux-53292cdb066950611e5bc2e0eb109c7edb42af78.tar.xz linux-53292cdb066950611e5bc2e0eb109c7edb42af78.zip |
drm/i915: Workaround to avoid lite restore with HEAD==TAIL
WaIdleLiteRestore is an execlists-only workaround, and requires the driver
to ensure that any context always has HEAD!=TAIL when attempting lite
restore.
Add two extra MI_NOOP instructions at the end of each request, but keep
the requests tail pointing before the MI_NOOPs. We may not need to
executed them, and this is why request->tail is sampled before adding
these extra instructions.
If we submit a context to the ELSP which has previously been submitted,
move the tail pointer past the MI_NOOPs. This ensures HEAD!=TAIL.
v2: Move overallocation to gen8_emit_request, and added note about
sampling request->tail in commit message (Chris).
v3: Remove redundant request->tail assignment in __i915_add_request, in
lrc mode this is already set in execlists_context_queue.
Do not add wa implementation details inside gem (Chris).
v4: Apply the wa whenever the req has been resubmitted and update
comment (Chris).
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
-rw-r--r-- | drivers/gpu/drm/i915/i915_gem.c | 3 | ||||
-rw-r--r-- | drivers/gpu/drm/i915/intel_lrc.c | 35 |
2 files changed, 36 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index d07c0b1fb498..53394f998a1f 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2377,10 +2377,11 @@ int __i915_add_request(struct intel_engine_cs *ring, ret = ring->add_request(ring); if (ret) return ret; + + request->tail = intel_ring_get_tail(ringbuf); } request->head = request_start; - request->tail = intel_ring_get_tail(ringbuf); /* Whilst this request exists, batch_obj will be on the * active_list, and so will hold the active reference. Only when this diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index fcb074bd55dc..09df74b8e917 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -393,6 +393,26 @@ static void execlists_context_unqueue(struct intel_engine_cs *ring) } } + if (IS_GEN8(ring->dev) || IS_GEN9(ring->dev)) { + /* + * WaIdleLiteRestore: make sure we never cause a lite + * restore with HEAD==TAIL + */ + if (req0 && req0->elsp_submitted) { + /* + * Apply the wa NOOPS to prevent ring:HEAD == req:TAIL + * as we resubmit the request. See gen8_emit_request() + * for where we prepare the padding after the end of the + * request. + */ + struct intel_ringbuffer *ringbuf; + + ringbuf = req0->ctx->engine[ring->id].ringbuf; + req0->tail += 8; + req0->tail &= ringbuf->size - 1; + } + } + WARN_ON(req1 && req1->elsp_submitted); execlists_submit_contexts(ring, req0->ctx, req0->tail, @@ -1315,7 +1335,12 @@ static int gen8_emit_request(struct intel_ringbuffer *ringbuf, u32 cmd; int ret; - ret = intel_logical_ring_begin(ringbuf, request->ctx, 6); + /* + * Reserve space for 2 NOOPs at the end of each request to be + * used as a workaround for not being allowed to do lite + * restore with HEAD==TAIL (WaIdleLiteRestore). + */ + ret = intel_logical_ring_begin(ringbuf, request->ctx, 8); if (ret) return ret; @@ -1333,6 +1358,14 @@ static int gen8_emit_request(struct intel_ringbuffer *ringbuf, intel_logical_ring_emit(ringbuf, MI_NOOP); intel_logical_ring_advance_and_submit(ringbuf, request->ctx, request); + /* + * Here we add two extra NOOPs as padding to avoid + * lite restore of a context with HEAD==TAIL. + */ + intel_logical_ring_emit(ringbuf, MI_NOOP); + intel_logical_ring_emit(ringbuf, MI_NOOP); + intel_logical_ring_advance(ringbuf); + return 0; } |