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drm/radeon: fix & improve ih ring handling v3

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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>
This commit is contained in:
Christian Koenig 2012-05-16 21:45:24 +02:00 • committed by Christian König
parent 6823d74003
commit c20dc3698d
5 changed files with 41 additions and 47 deletions
Download patch file Download diff file Expand all files Collapse all files

27
drivers/gpu/drm/radeon/si.c
View file

@ -2942,7 +2942,6 @@ static void si_disable_interrupts(struct radeon_device *rdev)
WREG32(IH_RB_RPTR, 0);
WREG32(IH_RB_WPTR, 0);
rdev->ih.enabled = false;
rdev->ih.wptr = 0;
rdev->ih.rptr = 0;
}
@ -3359,29 +3358,27 @@ int si_irq_process(struct radeon_device *rdev)
u32 rptr;
u32 src_id, src_data, ring_id;
u32 ring_index;
unsigned long flags;
bool queue_hotplug = false;
if (!rdev->ih.enabled || rdev->shutdown)
return IRQ_NONE;
wptr = si_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("si_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 */
si_irq_ack(rdev);
rdev->ih.wptr = wptr;
while (rptr != wptr) {
/* wptr/rptr are in bytes! */
ring_index = rptr / 4;
@ -3632,15 +3629,17 @@ restart_ih:
rptr += 16;
rptr &= rdev->ih.ptr_mask;
}
/* make sure wptr hasn't changed while processing */
wptr = si_get_ih_wptr(rdev);
if (wptr != rdev->ih.wptr)
goto restart_ih;
if (queue_hotplug)
schedule_work(&rdev->hotplug_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 = si_get_ih_wptr(rdev);
if (wptr != rptr)
goto restart_ih;
return IRQ_HANDLED;
}