[PATCH weston 2/2] compositor-drm: Fix inconsistency in finish frame timestamps

[Scott Moreau]

I picked this one up for gh next, since a lot of people were having a
problem with this. Animations stalling, especially.

- Scott

On Wed, Feb 13, 2013 at 7:06 AM, Ander Conselvan de Oliveira
<ander.conselvan.de.oliveira at intel.com> wrote:
> The page flip event timestamps comes from the monotonic clock, while
> idle_repaint() gets the time with gettimeofday(). That leads to
> inconsistent timestamps on the frame callbacks.
>
> Fix this by making the drm backend page flip to the current buffer and
> call weston_output_finish_frame() with the page flip event timestamp,
> instead of using gettimeofday().
> ---
>  src/compositor-drm.c |   34 ++++++++++++++++++++++++++++++----
>  src/compositor.c     |    6 +++++-
>  src/compositor.h     |    1 +
>  3 files changed, 36 insertions(+), 5 deletions(-)
>
> diff --git a/src/compositor-drm.c b/src/compositor-drm.c
> index f1f7343..e3ac572 100644
> --- a/src/compositor-drm.c
> +++ b/src/compositor-drm.c
> @@ -629,6 +629,26 @@ drm_output_repaint(struct weston_output *output_base,
>  }
>
>  static void
> +drm_output_start_repaint_loop(struct weston_output *output_base)
> +{
> +       struct drm_output *output = (struct drm_output *) output_base;
> +       struct drm_compositor *compositor = (struct drm_compositor *)
> +               output_base->compositor;
> +       uint32_t fb_id;
> +
> +       if (output->current)
> +               fb_id = output->current->fb_id;
> +       else
> +               fb_id = output->original_crtc->buffer_id;
> +
> +       if (drmModePageFlip(compositor->drm.fd, output->crtc_id, fb_id,
> +                           DRM_MODE_PAGE_FLIP_EVENT, output) < 0) {
> +               weston_log("queueing pageflip failed: %m\n");
> +               return;
> +       }
> +}
> +
> +static void
>  vblank_handler(int fd, unsigned int frame, unsigned int sec, unsigned int usec,
>                void *data)
>  {
> @@ -655,11 +675,16 @@ page_flip_handler(int fd, unsigned int frame,
>         struct drm_output *output = (struct drm_output *) data;
>         uint32_t msecs;
>
> -       output->page_flip_pending = 0;
> +       /* We don't set page_flip_pending on start_repaint_loop, in that case
> +        * we just want to page flip to the current buffer to get an accurate
> +        * timestamp */
> +       if (output->page_flip_pending) {
> +               drm_output_release_fb(output, output->current);
> +               output->current = output->next;
> +               output->next = NULL;
> +       }
>
> -       drm_output_release_fb(output, output->current);
> -       output->current = output->next;
> -       output->next = NULL;
> +       output->page_flip_pending = 0;
>
>         if (!output->vblank_pending) {
>                 msecs = sec * 1000 + usec / 1000;
> @@ -1636,6 +1661,7 @@ create_output_for_connector(struct drm_compositor *ec,
>         wl_list_insert(ec->base.output_list.prev, &output->base.link);
>
>         output->base.origin = output->base.current;
> +       output->base.start_repaint_loop = drm_output_start_repaint_loop;
>         output->base.repaint = drm_output_repaint;
>         output->base.destroy = drm_output_destroy;
>         output->base.assign_planes = drm_assign_planes;
> diff --git a/src/compositor.c b/src/compositor.c
> index 764d622..a0faba1 100644
> --- a/src/compositor.c
> +++ b/src/compositor.c
> @@ -1164,7 +1164,11 @@ idle_repaint(void *data)
>  {
>         struct weston_output *output = data;
>
> -       weston_output_finish_frame(output, weston_compositor_get_time());
> +       if (output->start_repaint_loop)
> +               output->start_repaint_loop(output);
> +       else
> +               weston_output_finish_frame(output,
> +                                          weston_compositor_get_time());
>  }
>
>  WL_EXPORT void
> diff --git a/src/compositor.h b/src/compositor.h
> index 004f931..34f81b5 100644
> --- a/src/compositor.h
> +++ b/src/compositor.h
> @@ -181,6 +181,7 @@ struct weston_output {
>         struct weston_mode *origin;
>         struct wl_list mode_list;
>
> +       void (*start_repaint_loop)(struct weston_output *output);
>         void (*repaint)(struct weston_output *output,
>                         pixman_region32_t *damage);
>         void (*destroy)(struct weston_output *output);
> --
> 1.7.10.4
>
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