On Tuesday, January 6, 2009 10:21 am Jesse Barnes wrote:
> In the absence of kernel mode setting, many drivers disable IRQs across VT
> switch. The core DRM vblank code is missing a check for this case however;
> even after IRQ disable, the vblank code will still have the vblank_enabled
> flag set, so unless we track the fact that they're disabled at IRQ
> uninstall time, when we VT switch back in we won't actually re-enable them,
> which means any apps waiting on vblank before the switch will hang.
>
> This patch does that and also adds a sanity check to the wait condition to
> look for the irq_enabled flag in general, as well as adding a wakeup to the
> IRQ uninstall path.
>
> This patch fixes fdo bug #18879, so hopefully we can apply it or another
> fix for this problem soon.
Here's an updated version I've been testing with. It removes the change to
drm_wait_vblank (we can still do it but it should be a separate patch).
Suspend/resume works for me with this one too, so if it looks good on
inspection I'd like to see it included. Even if it doesn't fix all the VT
switch/IRQ install bugs we have I think it's a step in the right direction
(IRQ uninstall really does imply vblank_enable == 0).
Thanks,
--
Jesse Barnes, Intel Open Source Technology Center
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 1e787f8..4cc8d3d 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -259,7 +259,8 @@ EXPORT_SYMBOL(drm_irq_install);
*/
int drm_irq_uninstall(struct drm_device * dev)
{
- int irq_enabled;
+ unsigned long irqflags;
+ int irq_enabled, i;
if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
return -EINVAL;
@@ -269,6 +270,16 @@ int drm_irq_uninstall(struct drm_device * dev)
dev->irq_enabled = 0;
mutex_unlock(&dev->struct_mutex);
+ /*
+ * Wake up any waiters so they don't hang.
+ */
+ spin_lock_irqsave(&dev->vbl_lock, irqflags);
+ for (i = 0; i < dev->num_crtcs; i++) {
+ DRM_WAKEUP(&dev->vbl_queue[i]);
+ dev->vblank_enabled[i] = 0;
+ }
+ spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
+
if (!irq_enabled)
return -EINVAL;
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