[PATCH 02/18] drm/exynos: use wait_event_timeout() for safety usage

[Daniel Kurtz]

On Wed, May 14, 2014 at 2:26 PM, YoungJun Cho <yj44.cho at samsung.com> wrote:
>
> There could be the case that the page flip operation isn't finished correctly
> with some abnormal condition such as panel reset. So this patch replaces
> wait_event() with wait_event_timeout() to avoid waiting for page flip completion
> infinitely.


This solution looks like we aren't really handling some conditions
completely (such as "panel reset"?). In cases where this timeout can
occur, shouldn't we be clearing pending_flip when we detect that the
flip will never complete?

-Dan

>
>
> Signed-off-by: YoungJun Cho <yj44.cho at samsung.com>
> Acked-by: Inki Dae <inki.dae at samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park at samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_crtc.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> index 95c9435..485fa26 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> @@ -69,8 +69,9 @@ static void exynos_drm_crtc_dpms(struct drm_crtc *crtc, int mode)
>
>         if (mode > DRM_MODE_DPMS_ON) {
>                 /* wait for the completion of page flip. */
> -               wait_event(exynos_crtc->pending_flip_queue,
> -                               atomic_read(&exynos_crtc->pending_flip) == 0);
> +               wait_event_timeout(exynos_crtc->pending_flip_queue,
> +                               !atomic_read(&exynos_crtc->pending_flip),
> +                               HZ/20);
>                 drm_vblank_off(crtc->dev, exynos_crtc->pipe);
>         }
>
> --
> 1.7.9.5
>
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