2019-06-28 12:06:37

by Bob Beckett

Subject: [PATCH v4 2/2] Revert "drm/vblank: Do not update vblank count if interrupts are already disabled."

If interrupts are already disabled, then the timestamp for the vblank
does not get updated, causing a stale timestamp to be reported to
userland while disabling crtcs.

This reverts commit 68036b08b91bc491ccc308f902616a570a49227c.

Signed-off-by: Robert Beckett <[email protected]>
---
drivers/gpu/drm/drm_vblank.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 7dabb2bdb733..aeb9734d7799 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -371,25 +371,23 @@ void drm_vblank_disable_and_save(struct drm_device *dev, unsigned int pipe)
spin_lock_irqsave(&dev->vblank_time_lock, irqflags);

/*
- * Update vblank count and disable vblank interrupts only if the
- * interrupts were enabled. This avoids calling the ->disable_vblank()
- * operation in atomic context with the hardware potentially runtime
- * suspended.
+ * Only disable vblank interrupts if they're enabled. This avoids
+ * calling the ->disable_vblank() operation in atomic context with the
+ * hardware potentially runtime suspended.
*/
- if (!vblank->enabled)
- goto out;
+ if (vblank->enabled) {
+ __disable_vblank(dev, pipe);
+ vblank->enabled = false;
+ }

/*
- * Update the count and timestamp to maintain the
+ * Always update the count and timestamp to maintain the
* appearance that the counter has been ticking all along until
* this time. This makes the count account for the entire time
* between drm_crtc_vblank_on() and drm_crtc_vblank_off().
*/
drm_update_vblank_count(dev, pipe, false);
- __disable_vblank(dev, pipe);
- vblank->enabled = false;

-out:
spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
}

--
2.18.0

2019-06-28 12:15:01

by Ville Syrjälä

Subject: Re: [PATCH v4 2/2] Revert "drm/vblank: Do not update vblank count if interrupts are already disabled."

On Fri, Jun 28, 2019 at 01:05:32PM +0100, Robert Beckett wrote:
> If interrupts are already disabled, then the timestamp for the vblank
> does not get updated, causing a stale timestamp to be reported to
> userland while disabling crtcs.
>
> This reverts commit 68036b08b91bc491ccc308f902616a570a49227c.

Please cc the people involved in that. And I'd drop the lkml cc.

>
> Signed-off-by: Robert Beckett <[email protected]>
> ---
> drivers/gpu/drm/drm_vblank.c | 18 ++++++++----------
> 1 file changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> index 7dabb2bdb733..aeb9734d7799 100644
> --- a/drivers/gpu/drm/drm_vblank.c
> +++ b/drivers/gpu/drm/drm_vblank.c
> @@ -371,25 +371,23 @@ void drm_vblank_disable_and_save(struct drm_device *dev, unsigned int pipe)
> spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
>
> /*
> - * Update vblank count and disable vblank interrupts only if the
> - * interrupts were enabled. This avoids calling the ->disable_vblank()
> - * operation in atomic context with the hardware potentially runtime
> - * suspended.
> + * Only disable vblank interrupts if they're enabled. This avoids
> + * calling the ->disable_vblank() operation in atomic context with the
> + * hardware potentially runtime suspended.
> */
> - if (!vblank->enabled)
> - goto out;
> + if (vblank->enabled) {
> + __disable_vblank(dev, pipe);
> + vblank->enabled = false;
> + }
>
> /*
> - * Update the count and timestamp to maintain the
> + * Always update the count and timestamp to maintain the
> * appearance that the counter has been ticking all along until
> * this time. This makes the count account for the entire time
> * between drm_crtc_vblank_on() and drm_crtc_vblank_off().
> */
> drm_update_vblank_count(dev, pipe, false);
> - __disable_vblank(dev, pipe);
> - vblank->enabled = false;
>
> -out:
> spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
> }
>
> --
> 2.18.0
>
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Ville Syrj?l?
Intel