Hi Geert,
Thank you for the patch.
On Thu, Jun 22, 2023 at 11:21:42AM +0200, Geert Uytterhoeven wrote:
> Turning a CRTC off will prevent a queued page flip from ever completing,
> potentially confusing userspace. Wait for queued page flips to complete
> before turning the CRTC off to avoid this.
>
> Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be>
Given that you're duplicating the rcar-du page flip handling code, I
have a feeling core helpers would be handy. It's not a blocker for this
series though, so
Reviewed-by: Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
> ---
> .../gpu/drm/renesas/shmobile/shmob_drm_crtc.c | 37 +++++++++++++++++++
> .../gpu/drm/renesas/shmobile/shmob_drm_crtc.h | 3 ++
> 2 files changed, 40 insertions(+)
>
> diff --git a/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
> b/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
> index 1d7fcf64bf2aab80..d2a0ac5f9368c11c 100644
> --- a/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
> +++ b/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
> @@ -285,11 +285,40 @@ void shmob_drm_crtc_finish_page_flip(struct
> shmob_drm_crtc *scrtc)
> scrtc->event = NULL;
> if (event) {
> drm_crtc_send_vblank_event(&scrtc->base, event);
> + wake_up(&scrtc->flip_wait);
> drm_crtc_vblank_put(&scrtc->base);
> }
> spin_unlock_irqrestore(&dev->event_lock, flags);
> }
>
> +static bool shmob_drm_crtc_page_flip_pending(struct shmob_drm_crtc *scrtc)
> +{
> + struct drm_device *dev = scrtc->base.dev;
> + unsigned long flags;
> + bool pending;
> +
> + spin_lock_irqsave(&dev->event_lock, flags);
> + pending = scrtc->event != NULL;
> + spin_unlock_irqrestore(&dev->event_lock, flags);
> +
> + return pending;
> +}
> +
> +static void shmob_drm_crtc_wait_page_flip(struct shmob_drm_crtc *scrtc)
> +{
> + struct drm_crtc *crtc = &scrtc->base;
> + struct shmob_drm_device *sdev = to_shmob_device(crtc->dev);
> +
> + if (wait_event_timeout(scrtc->flip_wait,
> + !shmob_drm_crtc_page_flip_pending(scrtc),
> + msecs_to_jiffies(50)))
> + return;
> +
> + dev_warn(sdev->dev, "page flip timeout\n");
> +
> + shmob_drm_crtc_finish_page_flip(scrtc);
> +}
> +
> /*
> -----------------------------------------------------------------------------
> * CRTC Functions
> */
> @@ -302,6 +331,12 @@ static void shmob_drm_crtc_stop(struct shmob_drm_crtc
> *scrtc)
> if (!scrtc->started)
> return;
>
> + /*
> + * Wait for page flip completion before stopping the CRTC as userspace
> + * expects page flips to eventually complete.
> + */
> + shmob_drm_crtc_wait_page_flip(scrtc);
> +
> /* Stop the LCDC. */
> shmob_drm_crtc_start_stop(scrtc, false);
>
> @@ -515,6 +550,8 @@ int shmob_drm_crtc_create(struct shmob_drm_device *sdev)
> unsigned int i;
> int ret;
>
> + init_waitqueue_head(&sdev->crtc.flip_wait);
> +
> sdev->crtc.dpms = DRM_MODE_DPMS_OFF;
>
> primary = shmob_drm_plane_create(sdev, 0);
> diff --git a/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.h
> b/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.h
> index 2c6d7541427581a6..b9863e026e8a9b83 100644
> --- a/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.h
> +++ b/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.h
> @@ -14,6 +14,8 @@
> #include <drm/drm_connector.h>
> #include <drm/drm_encoder.h>
>
> +#include <linux/wait.h>
> +
> #include <video/videomode.h>
>
> struct drm_pending_vblank_event;
> @@ -24,6 +26,7 @@ struct shmob_drm_crtc {
> struct drm_crtc base;
>
> struct drm_pending_vblank_event *event;
> + wait_queue_head_t flip_wait;
> int dpms;
>
> const struct shmob_drm_format_info *format;
--
Regards,
Laurent Pinchart
