If an error occurs in the front end when multi-lrc requests are getting generated we need to skip these in the backend but we still need to emit the breadcrumbs seqno. An issues arises because with multi-lrc breadcrumbs there is a handshake between the parent and children to make forward progress. If all the requests are not present this handshake doesn't work. To work around this, if multi-lrc request has an error we skip the handshake but still emit the breadcrumbs seqno.
v2: (John Harrison) - Add comment explaining the skipping of the handshake logic - Fix typos in the commit message v3: (John Harrison) - Fix up some comments about the math to NOP the ring
Signed-off-by: Matthew Brost matthew.brost@intel.com Reviewed-by: John Harrison John.C.Harrison@Intel.com --- .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 69 ++++++++++++++++++- 1 file changed, 66 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index 361fab2cae99..d7710debcd47 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -4070,8 +4070,8 @@ static int emit_bb_start_child_no_preempt_mid_batch(struct i915_request *rq, }
static u32 * -emit_fini_breadcrumb_parent_no_preempt_mid_batch(struct i915_request *rq, - u32 *cs) +__emit_fini_breadcrumb_parent_no_preempt_mid_batch(struct i915_request *rq, + u32 *cs) { struct intel_context *ce = rq->context; u8 i; @@ -4099,6 +4099,45 @@ emit_fini_breadcrumb_parent_no_preempt_mid_batch(struct i915_request *rq, get_children_go_addr(ce), 0);
+ return cs; +} + +/* + * If this true, a submission of multi-lrc requests had an error and the + * requests need to be skipped. The front end (execuf IOCTL) should've called + * i915_request_skip which squashes the BB but we still need to emit the fini + * breadrcrumbs seqno write. At this point we don't know how many of the + * requests in the multi-lrc submission were generated so we can't do the + * handshake between the parent and children (e.g. if 4 requests should be + * generated but 2nd hit an error only 1 would be seen by the GuC backend). + * Simply skip the handshake, but still emit the breadcrumbd seqno, if an error + * has occurred on any of the requests in submission / relationship. + */ +static inline bool skip_handshake(struct i915_request *rq) +{ + return test_bit(I915_FENCE_FLAG_SKIP_PARALLEL, &rq->fence.flags); +} + +static u32 * +emit_fini_breadcrumb_parent_no_preempt_mid_batch(struct i915_request *rq, + u32 *cs) +{ + struct intel_context *ce = rq->context; + + GEM_BUG_ON(!intel_context_is_parent(ce)); + + if (unlikely(skip_handshake(rq))) { + /* + * NOP everything in __emit_fini_breadcrumb_parent_no_preempt_mid_batch, + * the -6 comes from the length of the emits below. + */ + memset(cs, 0, sizeof(u32) * + (ce->engine->emit_fini_breadcrumb_dw - 6)); + cs += ce->engine->emit_fini_breadcrumb_dw - 6; + } else { + cs = __emit_fini_breadcrumb_parent_no_preempt_mid_batch(rq, cs); + } + /* Emit fini breadcrumb */ cs = gen8_emit_ggtt_write(cs, rq->fence.seqno, @@ -4115,7 +4154,8 @@ emit_fini_breadcrumb_parent_no_preempt_mid_batch(struct i915_request *rq, }
static u32 * -emit_fini_breadcrumb_child_no_preempt_mid_batch(struct i915_request *rq, u32 *cs) +__emit_fini_breadcrumb_child_no_preempt_mid_batch(struct i915_request *rq, + u32 *cs) { struct intel_context *ce = rq->context; struct intel_context *parent = intel_context_to_parent(ce); @@ -4142,6 +4182,29 @@ emit_fini_breadcrumb_child_no_preempt_mid_batch(struct i915_request *rq, u32 *cs *cs++ = get_children_go_addr(parent); *cs++ = 0;
+ return cs; +} + +static u32 * +emit_fini_breadcrumb_child_no_preempt_mid_batch(struct i915_request *rq, + u32 *cs) +{ + struct intel_context *ce = rq->context; + + GEM_BUG_ON(!intel_context_is_child(ce)); + + if (unlikely(skip_handshake(rq))) { + /* + * NOP everything in __emit_fini_breadcrumb_child_no_preempt_mid_batch, + * the -6 comes from the length of the emits below. + */ + memset(cs, 0, sizeof(u32) * + (ce->engine->emit_fini_breadcrumb_dw - 6)); + cs += ce->engine->emit_fini_breadcrumb_dw - 6; + } else { + cs = __emit_fini_breadcrumb_child_no_preempt_mid_batch(rq, cs); + } + /* Emit fini breadcrumb */ cs = gen8_emit_ggtt_write(cs, rq->fence.seqno,