i915: Fix i915 suspend delay

d7b9935a · Linus Torvalds <[email protected]> · 2011-01-20 13:19:55 -08:00

During system suspend, the "wait for ring buffer to empty" loop would
always time out after three seconds, because the faster cached ring
buffer head read would always return zero.  Force the slow-and-careful
PIO read on all but the first iterations of the loop to fix it.

This also removes the unused (and useless) 'actual_head' variable that
tried to approximate doing this, but did it incorrectly.

Cc: Chris Wilson <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Jesse Barnes <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: DRI mailing list <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: d7b9935a347ae954be907ea3d5eb4564ff124c53
Parents: b23fffd7

Changes

2 files changed · +3 −3

File	Status	Add	Del	Content
drivers/gpu/drm/i915/intel_ringbuffer.c	modified	+3	−2	View file
drivers/gpu/drm/i915/intel_ringbuffer.h	modified	+0	−1	View file

drivers/gpu/drm/i915/intel_ringbuffer.c

View file

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 03e3370..f6b9baa 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -928,6 +928,7 @@ static int intel_wrap_ring_buffer(struct intel_ring_buffer *ring)
 
 int intel_wait_ring_buffer(struct intel_ring_buffer *ring, int n)
 {
+	int reread = 0;
 	struct drm_device *dev = ring->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	unsigned long end;
@@ -940,9 +941,8 @@ int intel_wait_ring_buffer(struct intel_ring_buffer *ring, int n)
 		 * fallback to the slow and accurate path.
 		 */
 		head = intel_read_status_page(ring, 4);
-		if (head < ring->actual_head)
+		if (reread)
 			head = I915_READ_HEAD(ring);
-		ring->actual_head = head;
 		ring->head = head & HEAD_ADDR;
 		ring->space = ring->head - (ring->tail + 8);
 		if (ring->space < 0)
@@ -961,6 +961,7 @@ int intel_wait_ring_buffer(struct intel_ring_buffer *ring, int n)
 		msleep(1);
 		if (atomic_read(&dev_priv->mm.wedged))
 			return -EAGAIN;
+		reread = 1;
 	} while (!time_after(jiffies, end));
 	trace_i915_ring_wait_end (dev);
 	return -EBUSY;

drivers/gpu/drm/i915/intel_ringbuffer.h

View file

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index be9087e..5b0abfa 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -47,7 +47,6 @@ struct  intel_ring_buffer {
 	struct		drm_device *dev;
 	struct		drm_i915_gem_object *obj;
 
-	u32		actual_head;
 	u32		head;
 	u32		tail;
 	int		space;