diff options
| -rw-r--r-- | drivers/gpu/drm/i915/i915_irq.c | 38 |
1 files changed, 26 insertions, 12 deletions
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index acf1ab3..9ef241f 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -2530,29 +2530,43 @@ static struct intel_ring_buffer * semaphore_waits_for(struct intel_ring_buffer *ring, u32 *seqno) { struct drm_i915_private *dev_priv = ring->dev->dev_private; - u32 cmd, ipehr, acthd, acthd_min; + u32 cmd, ipehr, head; + int i; ipehr = I915_READ(RING_IPEHR(ring->mmio_base)); if ((ipehr & ~(0x3 << 16)) != (MI_SEMAPHORE_MBOX | MI_SEMAPHORE_COMPARE | MI_SEMAPHORE_REGISTER)) return NULL; - /* ACTHD is likely pointing to the dword after the actual command, - * so scan backwards until we find the MBOX. + /* + * HEAD is likely pointing to the dword after the actual command, + * so scan backwards until we find the MBOX. But limit it to just 3 + * dwords. Note that we don't care about ACTHD here since that might + * point at at batch, and semaphores are always emitted into the + * ringbuffer itself. */ - acthd = intel_ring_get_active_head(ring) & HEAD_ADDR; - acthd_min = max((int)acthd - 3 * 4, 0); - do { - cmd = ioread32(ring->virtual_start + acthd); + head = I915_READ_HEAD(ring) & HEAD_ADDR; + + for (i = 4; i; --i) { + /* + * Be paranoid and presume the hw has gone off into the wild - + * our ring is smaller than what the hardware (and hence + * HEAD_ADDR) allows. Also handles wrap-around. + */ + head &= ring->size - 1; + + /* This here seems to blow up */ + cmd = ioread32(ring->virtual_start + head); if (cmd == ipehr) break; - acthd -= 4; - if (acthd < acthd_min) - return NULL; - } while (1); + head -= 4; + } + + if (!i) + return NULL; - *seqno = ioread32(ring->virtual_start+acthd+4)+1; + *seqno = ioread32(ring->virtual_start + head + 4) + 1; return &dev_priv->ring[(ring->id + (((ipehr >> 17) & 1) + 1)) % 3]; } |
