static int semaphore_passed(struct intel_engine_cs *engine) { struct drm_i915_private *dev_priv = engine->i915; struct intel_engine_cs *signaller; u32 seqno; engine->hangcheck.deadlock++; signaller = semaphore_waits_for(engine, &seqno); if (signaller == NULL) return -1; if (IS_ERR(signaller)) return 0; /* Prevent pathological recursion due to driver bugs */ if (signaller->hangcheck.deadlock >= I915_NUM_ENGINES) return -1; if (i915_seqno_passed(intel_engine_get_seqno(signaller), seqno)) return 1; /* cursory check for an unkickable deadlock */ if (I915_READ_CTL(signaller) & RING_WAIT_SEMAPHORE && semaphore_passed(signaller) < 0) return -1; return 0; }
static int init_ring_common(struct intel_ring_buffer *ring) { drm_i915_private_t *dev_priv = ring->dev->dev_private; struct drm_i915_gem_object *obj = ring->obj; u32 head; /* Stop the ring if it's running. */ I915_WRITE_CTL(ring, 0); I915_WRITE_HEAD(ring, 0); ring->write_tail(ring, 0); /* Initialize the ring. */ I915_WRITE_START(ring, obj->gtt_offset); head = I915_READ_HEAD(ring) & HEAD_ADDR; /* G45 ring initialization fails to reset head to zero */ if (head != 0) { DRM_DEBUG_KMS("%s head not reset to zero " "ctl %08x head %08x tail %08x start %08x\n", ring->name, I915_READ_CTL(ring), I915_READ_HEAD(ring), I915_READ_TAIL(ring), I915_READ_START(ring)); I915_WRITE_HEAD(ring, 0); if (I915_READ_HEAD(ring) & HEAD_ADDR) { DRM_ERROR("failed to set %s head to zero " "ctl %08x head %08x tail %08x start %08x\n", ring->name, I915_READ_CTL(ring), I915_READ_HEAD(ring), I915_READ_TAIL(ring), I915_READ_START(ring)); } } I915_WRITE_CTL(ring, ((ring->size - PAGE_SIZE) & RING_NR_PAGES) | RING_REPORT_64K | RING_VALID); /* If the head is still not zero, the ring is dead */ if ((I915_READ_CTL(ring) & RING_VALID) == 0 || I915_READ_START(ring) != obj->gtt_offset || (I915_READ_HEAD(ring) & HEAD_ADDR) != 0) { DRM_ERROR("%s initialization failed " "ctl %08x head %08x tail %08x start %08x\n", ring->name, I915_READ_CTL(ring), I915_READ_HEAD(ring), I915_READ_TAIL(ring), I915_READ_START(ring)); return -EIO; } if (!drm_core_check_feature(ring->dev, DRIVER_MODESET)) i915_kernel_lost_context(ring->dev); else { ring->head = I915_READ_HEAD(ring); ring->tail = I915_READ_TAIL(ring) & TAIL_ADDR; ring->space = ring_space(ring); } return 0; }