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;
}
