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drm/armada: use xchg() to atomically update dplane->old_fb

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Rather than using a spinlock, use xchg() to atomically update
dplane->old_fb.  This allows us to eliminate dplane->lock.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2015-07-15 18:11:24 +01:00
parent fecfdb2db8
commit 66377efa3f
1 changed files with 2 additions and 10 deletions
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12
drivers/gpu/drm/armada/armada_overlay.c
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@ -31,7 +31,6 @@ struct armada_ovl_plane_properties {
struct armada_ovl_plane {
struct drm_plane base;
spinlock_t lock;
struct drm_framebuffer *old_fb;
uint32_t src_hw;
uint32_t dst_hw;
@ -76,10 +75,7 @@ static void armada_ovl_retire_fb(struct armada_ovl_plane *dplane,
{
struct drm_framebuffer *old_fb;
spin_lock(&dplane->lock);
old_fb = dplane->old_fb;
dplane->old_fb = fb;
spin_unlock(&dplane->lock);
old_fb = xchg(&dplane->old_fb, fb);
if (old_fb)
armada_drm_queue_unref_work(dplane->base.dev, old_fb);
@ -289,10 +285,7 @@ static int armada_ovl_plane_disable(struct drm_plane *plane)
if (plane->fb)
drm_framebuffer_unreference(plane->fb);
spin_lock_irq(&dplane->lock);
fb = dplane->old_fb;
dplane->old_fb = NULL;
spin_unlock_irq(&dplane->lock);
fb = xchg(&dplane->old_fb, NULL);
if (fb)
drm_framebuffer_unreference(fb);
@ -464,7 +457,6 @@ int armada_overlay_plane_create(struct drm_device *dev, unsigned long crtcs)
if (!dplane)
return -ENOMEM;
spin_lock_init(&dplane->lock);
init_waitqueue_head(&dplane->vbl.wait);
armada_drm_vbl_event_init(&dplane->vbl.update, armada_ovl_plane_vbl,
dplane);