[Intel-gfx] [PATCH 04/10] drm/i915: drop polled waits from i915_wait_request

[Ben Widawsky]

The only time irq_get should fail is during unload or suspend. Both of
these points should try to quiesce the GPU before disabling interrupts
and so the atomic polling should never occur.

This was recommended by Chris Wilson as a way of reducing added
complexity to the polled wait which I introduced in an RFC patch.

09:57 < ickle_> it's only there as a fudge for waiting after irqs
after uninstalled during s&r, we aren't actually meant to hit it
09:57 < ickle_> so maybe we should just kill the code there and fix the breakage

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Ben Widawsky <benjamin.widawsky at intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c |   25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a86a6ee..6ad52d3 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1892,22 +1892,19 @@ i915_wait_request(struct intel_ring_buffer *ring,
 	if (!i915_seqno_passed(ring->get_seqno(ring), seqno)) {
 		trace_i915_gem_request_wait_begin(ring, seqno);
 
-		if (ring->irq_get(ring)) {
-			if (dev_priv->mm.interruptible)
-				ret = wait_event_interruptible(ring->irq_queue,
-							       i915_seqno_passed(ring->get_seqno(ring), seqno)
-							       || atomic_read(&dev_priv->mm.wedged));
-			else
-				wait_event(ring->irq_queue,
-					   i915_seqno_passed(ring->get_seqno(ring), seqno)
-					   || atomic_read(&dev_priv->mm.wedged));
+		if (WARN_ON(!ring->irq_get(ring)))
+			return -EBUSY;
 
-			ring->irq_put(ring);
-		} else if (wait_for_atomic(i915_seqno_passed(ring->get_seqno(ring),
-							     seqno) ||
-					   atomic_read(&dev_priv->mm.wedged), 3000))
-			ret = -EBUSY;
+		if (dev_priv->mm.interruptible)
+			ret = wait_event_interruptible(ring->irq_queue,
+						       i915_seqno_passed(ring->get_seqno(ring), seqno)
+						       || atomic_read(&dev_priv->mm.wedged));
+		else
+			wait_event(ring->irq_queue,
+				   i915_seqno_passed(ring->get_seqno(ring), seqno)
+				   || atomic_read(&dev_priv->mm.wedged));
 
+		ring->irq_put(ring);
 		trace_i915_gem_request_wait_end(ring, seqno);
 	}
 	if (atomic_read(&dev_priv->mm.wedged))
-- 
1.7.10