diff options
Diffstat (limited to '0013-drm-i915-gt-Detect-if-we-miss-WaIdleLiteRestore.patch')
| -rw-r--r-- | 0013-drm-i915-gt-Detect-if-we-miss-WaIdleLiteRestore.patch | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/0013-drm-i915-gt-Detect-if-we-miss-WaIdleLiteRestore.patch b/0013-drm-i915-gt-Detect-if-we-miss-WaIdleLiteRestore.patch new file mode 100644 index 0000000..5ee3f39 --- /dev/null +++ b/0013-drm-i915-gt-Detect-if-we-miss-WaIdleLiteRestore.patch @@ -0,0 +1,130 @@ +From 8c19c0f7eacb125b9a097d080a385d527f8ff836 Mon Sep 17 00:00:00 2001 +From: Chris Wilson <chris@chris-wilson.co.uk> +Date: Mon, 30 Dec 2019 11:15:30 +0000 +Subject: drm/i915/gt: Detect if we miss WaIdleLiteRestore + +In order to avoid confusing the HW, we must never submit an empty ring +during lite-restore, that is we should always advance the RING_TAIL +before submitting to stay ahead of the RING_HEAD. + +Normally this is prevented by keeping a couple of spare NOPs in the +request->wa_tail so that on resubmission we can advance the tail. This +relies on the request only being resubmitted once, which is the normal +condition as it is seen once for ELSP[1] and then later in ELSP[0]. On +preemption, the requests are unwound and the tail reset back to the +normal end point (as we know the request is incomplete and therefore its +RING_HEAD is even earlier). + +However, if this w/a should fail we would try and resubmit the request +with the RING_TAIL already set to the location of this request's wa_tail +potentially causing a GPU hang. We can spot when we do try and +incorrectly resubmit without advancing the RING_TAIL and spare any +embarrassment by forcing the context restore. + +In the case of preempt-to-busy, we leave the requests running on the HW +while we unwind. As the ring is still live, we cannot rewind our +rq->tail without forcing a reload so leave it set to rq->wa_tail and +only force a reload if we resubmit after a lite-restore. (Normally, the +forced reload will be a part of the preemption event.) + +Fixes: 22b7a426bbe1 ("drm/i915/execlists: Preempt-to-busy") +Closes: https://gitlab.freedesktop.org/drm/intel/issues/673 +Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> +Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> +Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> +Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> +Cc: stable@vger.kernel.org +Link: https://patchwork.freedesktop.org/patch/msgid/20191209023215.3519970-1-chris@chris-wilson.co.uk +(cherry picked from commit 82c69bf58650e644c61aa2bf5100b63a1070fd2f) +--- + drivers/gpu/drm/i915/gt/intel_lrc.c | 42 ++++++++++++++++++------------------- + 1 file changed, 20 insertions(+), 22 deletions(-) + +diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c +index 06a506c29463..6600b2e08fe3 100644 +--- a/drivers/gpu/drm/i915/gt/intel_lrc.c ++++ b/drivers/gpu/drm/i915/gt/intel_lrc.c +@@ -471,12 +471,6 @@ lrc_descriptor(struct intel_context *ce, struct intel_engine_cs *engine) + return desc; + } + +-static void unwind_wa_tail(struct i915_request *rq) +-{ +- rq->tail = intel_ring_wrap(rq->ring, rq->wa_tail - WA_TAIL_BYTES); +- assert_ring_tail_valid(rq->ring, rq->tail); +-} +- + static struct i915_request * + __unwind_incomplete_requests(struct intel_engine_cs *engine) + { +@@ -495,7 +489,6 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine) + continue; /* XXX */ + + __i915_request_unsubmit(rq); +- unwind_wa_tail(rq); + + /* + * Push the request back into the queue for later resubmission. +@@ -649,13 +642,29 @@ execlists_schedule_out(struct i915_request *rq) + i915_request_put(rq); + } + +-static u64 execlists_update_context(const struct i915_request *rq) ++static u64 execlists_update_context(struct i915_request *rq) + { + struct intel_context *ce = rq->hw_context; +- u64 desc; ++ u64 desc = ce->lrc_desc; ++ u32 tail; + +- ce->lrc_reg_state[CTX_RING_TAIL + 1] = +- intel_ring_set_tail(rq->ring, rq->tail); ++ /* ++ * WaIdleLiteRestore:bdw,skl ++ * ++ * We should never submit the context with the same RING_TAIL twice ++ * just in case we submit an empty ring, which confuses the HW. ++ * ++ * We append a couple of NOOPs (gen8_emit_wa_tail) after the end of ++ * the normal request to be able to always advance the RING_TAIL on ++ * subsequent resubmissions (for lite restore). Should that fail us, ++ * and we try and submit the same tail again, force the context ++ * reload. ++ */ ++ tail = intel_ring_set_tail(rq->ring, rq->tail); ++ if (unlikely(ce->lrc_reg_state[CTX_RING_TAIL + 1] == tail)) ++ desc |= CTX_DESC_FORCE_RESTORE; ++ ce->lrc_reg_state[CTX_RING_TAIL + 1] = tail; ++ rq->tail = rq->wa_tail; + + /* + * Make sure the context image is complete before we submit it to HW. +@@ -674,7 +683,6 @@ static u64 execlists_update_context(const struct i915_request *rq) + */ + mb(); + +- desc = ce->lrc_desc; + ce->lrc_desc &= ~CTX_DESC_FORCE_RESTORE; + + return desc; +@@ -1149,16 +1157,6 @@ static void execlists_dequeue(struct intel_engine_cs *engine) + if (!list_is_last(&last->sched.link, + &engine->active.requests)) + return; +- +- /* +- * WaIdleLiteRestore:bdw,skl +- * Apply the wa NOOPs to prevent +- * ring:HEAD == rq:TAIL as we resubmit the +- * request. See gen8_emit_fini_breadcrumb() for +- * where we prepare the padding after the +- * end of the request. +- */ +- last->tail = last->wa_tail; + } + } + +-- +cgit v1.2.1-1-g437b + + |