drm/radeon: fix & improve ih ring handling v3
The spinlock was actually there to protect the
rptr, but rptr was read outside of the locked area.
Also we don't really need a spinlock here, an
atomic should to quite fine since we only need to
prevent it from being reentrant.
v2: Keep the spinlock....
v3: Back to an atomic again after finding & fixing the real bug.
Signed-off-by: Christian Koenig <christian.koenig@amd.com>
diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index aced97b..b487c69 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -2858,7 +2858,6 @@
WREG32(IH_RB_RPTR, 0);
WREG32(IH_RB_WPTR, 0);
rdev->ih.enabled = false;
- rdev->ih.wptr = 0;
rdev->ih.rptr = 0;
}
@@ -3310,7 +3309,6 @@
u32 rptr;
u32 src_id, src_data;
u32 ring_index;
- unsigned long flags;
bool queue_hotplug = false;
bool queue_hdmi = false;
@@ -3322,24 +3320,21 @@
RREG32(IH_RB_WPTR);
wptr = r600_get_ih_wptr(rdev);
+
+restart_ih:
+ /* is somebody else already processing irqs? */
+ if (atomic_xchg(&rdev->ih.lock, 1))
+ return IRQ_NONE;
+
rptr = rdev->ih.rptr;
DRM_DEBUG("r600_irq_process start: rptr %d, wptr %d\n", rptr, wptr);
- spin_lock_irqsave(&rdev->ih.lock, flags);
-
- if (rptr == wptr) {
- spin_unlock_irqrestore(&rdev->ih.lock, flags);
- return IRQ_NONE;
- }
-
-restart_ih:
/* Order reading of wptr vs. reading of IH ring data */
rmb();
/* display interrupts */
r600_irq_ack(rdev);
- rdev->ih.wptr = wptr;
while (rptr != wptr) {
/* wptr/rptr are in bytes! */
ring_index = rptr / 4;
@@ -3493,17 +3488,19 @@
rptr += 16;
rptr &= rdev->ih.ptr_mask;
}
- /* make sure wptr hasn't changed while processing */
- wptr = r600_get_ih_wptr(rdev);
- if (wptr != rdev->ih.wptr)
- goto restart_ih;
if (queue_hotplug)
schedule_work(&rdev->hotplug_work);
if (queue_hdmi)
schedule_work(&rdev->audio_work);
rdev->ih.rptr = rptr;
WREG32(IH_RB_RPTR, rdev->ih.rptr);
- spin_unlock_irqrestore(&rdev->ih.lock, flags);
+ atomic_set(&rdev->ih.lock, 0);
+
+ /* make sure wptr hasn't changed while processing */
+ wptr = r600_get_ih_wptr(rdev);
+ if (wptr != rptr)
+ goto restart_ih;
+
return IRQ_HANDLED;
}