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i915: Fix i915 suspend delay 

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 <chris@chris-wilson.co.uk>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Dave Airlie <airlied@linux.ie>
Cc: DRI mailing list <dri-devel@lists.freedesktop.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2011-01-20 13:19:55 -08:00
parent b23fffd778
commit d7b9935a34
2 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/gpu/drm/i915/intel_ringbuffer.c
View File

@ -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;

1
drivers/gpu/drm/i915/intel_ringbuffer.h
View File

@ -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;