[PATCH] drm/doc: clarify how to acquire required vblank event reference

[PATCH] drm/doc: clarify how to acquire required vblank event reference

[Stefan Agner]

As a driver write it is not entirely obvious that a reference to
the event e mentioned in the doc can be obtained via
drm_crtc_vblank_get(). Clarify how to obtain the reference.

Signed-off-by: Stefan Agner <stefan@agner.ch>
---
 drivers/gpu/drm/drm_vblank.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 28cdcf76b6f9..7610ff466ef9 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -873,8 +873,8 @@ static void send_vblank_event(struct drm_device *dev,
  * handler by calling drm_crtc_send_vblank_event() and make sure that there's no
  * possible race with the hardware committing the atomic update.
  *
- * Caller must hold a vblank reference for the event @e, which will be dropped
- * when the next vblank arrives.
+ * Caller must hold a vblank reference for the event @e acquired by a
+ * drm_crtc_vblank_get(), which will be dropped when the next vblank arrives.
  */
 void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
 			       struct drm_pending_vblank_event *e)
-- 
2.18.0

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Re: [PATCH] drm/doc: clarify how to acquire required vblank event reference

[Daniel Vetter]

On Tue, Aug 07, 2018 at 10:11:43PM +0200, Stefan Agner wrote:
> As a driver write it is not entirely obvious that a reference to
> the event e mentioned in the doc can be obtained via
> drm_crtc_vblank_get(). Clarify how to obtain the reference.
> 
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> ---
>  drivers/gpu/drm/drm_vblank.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> index 28cdcf76b6f9..7610ff466ef9 100644
> --- a/drivers/gpu/drm/drm_vblank.c
> +++ b/drivers/gpu/drm/drm_vblank.c
> @@ -873,8 +873,8 @@ static void send_vblank_event(struct drm_device *dev,
>   * handler by calling drm_crtc_send_vblank_event() and make sure that there's no
>   * possible race with the hardware committing the atomic update.
>   *
> - * Caller must hold a vblank reference for the event @e, which will be dropped
> - * when the next vblank arrives.
> + * Caller must hold a vblank reference for the event @e acquired by a
> + * drm_crtc_vblank_get(), which will be dropped when the next vblank arrives.

Thanks for this clarification, patch applied.
-Daniel

>   */
>  void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
>  			       struct drm_pending_vblank_event *e)
> -- 
> 2.18.0
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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