[PATCH 2/2] drm/udl: Implement page_flip ioctl

[David Herrmann]

Hi

On Thu, Jul 3, 2014 at 12:13 AM, Stéphane Marchesin
<marcheu at chromium.org> wrote:
> This is a very crude page_flip implementation for UDL. There are ways
> to make it better (make it asynchronous, make it do actual vsynced
> flips...) but that's for another patch.
>
> Signed-off-by: Stéphane Marchesin <marcheu at chromium.org>
> ---
>  drivers/gpu/drm/udl/udl_modeset.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
> index cddc4fc..7dc3bd8 100644
> --- a/drivers/gpu/drm/udl/udl_modeset.c
> +++ b/drivers/gpu/drm/udl/udl_modeset.c
> @@ -363,6 +363,26 @@ static void udl_crtc_destroy(struct drm_crtc *crtc)
>         kfree(crtc);
>  }
>
> +static int udl_crtc_page_flip(struct drm_crtc *crtc,
> +                             struct drm_framebuffer *fb,
> +                             struct drm_pending_vblank_event *event,
> +                             uint32_t page_flip_flags)
> +{
> +       struct udl_framebuffer *ufb = to_udl_fb(fb);
> +       struct drm_device *dev = crtc->dev;
> +       unsigned long flags;
> +
> +       udl_handle_damage(ufb, 0, 0, fb->width, fb->height);
> +
> +       spin_lock_irqsave(&dev->event_lock, flags);
> +       if (event)
> +               drm_send_vblank_event(dev, 0, event);
> +       spin_unlock_irqrestore(&dev->event_lock, flags);
> +       crtc->fb = fb;

Doesn't this break user-space that expects page-flip events to not
occur more often than the refresh-rate? For instance, weston
re-renders on each page-flip event. With this patch, it will never
sleep on udl as it immediately gets the page-flip event back?

Thanks
David

> +
> +       return 0;
> +}
> +
>  static void udl_crtc_prepare(struct drm_crtc *crtc)
>  {
>  }
> @@ -384,6 +404,7 @@ static struct drm_crtc_helper_funcs udl_helper_funcs = {
>  static const struct drm_crtc_funcs udl_crtc_funcs = {
>         .set_config = drm_crtc_helper_set_config,
>         .destroy = udl_crtc_destroy,
> +       .page_flip = udl_crtc_page_flip,
>  };
>
>  static int udl_crtc_init(struct drm_device *dev)
> --
> 2.0.0.526.g5318336
>
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