[PATCH 09/12] drm/i915: timeout parameter for seqno wait

[Ben Widawsky <ben@bwidawsk.net>]

Insert a wait parameter in the code so we can possibly timeout on a
seqno wait if need be. The code should be functionally the same as
before because all the callers will continue to retry if an arbitrary
timeout elapses.

We'd like to have nanosecond granularity, but the only way to do this is
with hrtimer, and that doesn't fit well with the needs of this code.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_gem.c |   58 +++++++++++++++++++++++++++++++--------
 1 file changed, 46 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0ae1a73..f054439 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1820,10 +1820,23 @@ i915_gem_retire_work_handler(struct work_struct *work)
 }
 
 static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno,
-			bool interruptible)
+			bool interruptible, long *usecs)
 {
 	drm_i915_private_t *dev_priv = ring->dev->dev_private;
-	int ret = 0;
+	bool wait_forever = false;
+	long timeout, end;
+
+	if (usecs == NULL || ((*usecs) < 0)) {
+		wait_forever = true;
+		timeout = msecs_to_jiffies(100);
+	} else
+		timeout = usecs_to_jiffies(*usecs);
+
+	if (i915_seqno_passed(ring->get_seqno(ring), seqno))
+		return 0;
+
+	if (WARN_ON(!ring->irq_get(ring)))
+		return -ENODEV;
 
 	if (i915_seqno_passed(ring->get_seqno(ring), seqno))
 		return 0;
@@ -1836,17 +1849,40 @@ static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno,
 	(i915_seqno_passed(ring->get_seqno(ring), seqno) || \
 	atomic_read(&dev_priv->mm.wedged))
 
+	trace_i915_gem_request_wait_begin(ring, seqno);
+again:
 	if (interruptible)
-		ret = wait_event_interruptible(ring->irq_queue,
-					       EXIT_COND);
+		end = wait_event_interruptible_timeout(ring->irq_queue,
+						       EXIT_COND,
+						       timeout);
 	else
-		wait_event(ring->irq_queue, EXIT_COND);
+		end = wait_event_timeout(ring->irq_queue, EXIT_COND, timeout);
+#undef EXIT_COND
+
+	if (atomic_read(&dev_priv->mm.wedged))
+		end = -EAGAIN;
+
+	if (end == 0 && wait_forever)
+		goto again;
 
-	ring->irq_put(ring);
 	trace_i915_gem_request_wait_end(ring, seqno);
-#undef EXIT_COND
+	ring->irq_put(ring);
 
-	return ret;
+	if (!wait_forever) {
+		BUG_ON(end == 0);
+		*usecs = jiffies_to_usecs(timeout - end);
+	}
+
+	switch (end) {
+	case -EAGAIN: /* Wedged */
+	case -ERESTARTSYS: /* Signal */
+		return (int)end;
+	case 0: /* Tiemout */
+		return -ETIME;
+	default: /* Completed */
+		WARN_ON(end < 0); /* We're not aware of other errors */
+		return 0;
+	}
 }
 
 /**
@@ -1891,9 +1927,7 @@ i915_wait_request(struct intel_ring_buffer *ring,
 		seqno = request->seqno;
 	}
 
-	ret = __wait_seqno(ring, seqno, dev_priv->mm.interruptible);
-	if (atomic_read(&dev_priv->mm.wedged))
-		ret = -EAGAIN;
+	ret = __wait_seqno(ring, seqno, dev_priv->mm.interruptible, NULL);
 
 	return ret;
 }
@@ -2981,7 +3015,7 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
 	if (seqno == 0)
 		return 0;
 
-	ret = __wait_seqno(ring, seqno, true);
+	ret = __wait_seqno(ring, seqno, true, NULL);
 	if (ret == 0)
 		queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, 0);
 
-- 
1.7.10