Re: [PATCH 05/36] drm/atomic: Add drm_atomic_plane_get_crtc_state()

From: Daniel Vetter
Date: Tue Jan 20 2015 - 06:10:27 EST


On Tue, Jan 20, 2015 at 11:48:24AM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding@xxxxxxxxxx>
>
> This function is useful to obtain the state of the CRTC that a plane is
> being attached to.
>
> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
> ---
> include/drm/drm_atomic.h | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index 51168a8b723a..ddca107e5cce 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -75,4 +75,25 @@ int __must_check drm_atomic_check_only(struct drm_atomic_state *state);
> int __must_check drm_atomic_commit(struct drm_atomic_state *state);
> int __must_check drm_atomic_async_commit(struct drm_atomic_state *state);
>
> +/**
> + * drm_atomic_plane_get_crtc_state - obtain atomic state of the CRTC that a
> + * plane is being attached to
> + * @state: atomic state of plane
> + *
> + * Getting the atomic state of the CRTC that a given plane being attached to
> + * is non-trivial. We need to look at the global atomic state that the plane
> + * state is part of and extract the CRTC state using the CRTC's index. Using
> + * the drm_atomic_get_crtc_state() helper we make sure to acquire the proper
> + * locks, too.
> + *
> + * RETURNS:
> + * The atomic state of the CRTC that the plane is being attached to, or an
> + * ERR_PTR()-encoded negative error code on failure.
> + */
> +static inline struct drm_crtc_state *
> +drm_atomic_plane_get_crtc_state(struct drm_plane_state *state)
> +{
> + return drm_atomic_get_crtc_state(state->state, state->crtc);

Hm, imo open-coding this is totally ok. Actually better since state->crtc
might be NULL, and hiding that isn't a good idea.

If you have a atomic_plane_disable hook then ->crtc is guaranteed to be
non-NULL in atomic_plane_update, but being explicit here is imo a feature.
So nacked from my side.
-Daniel

> +}
> +
> #endif /* DRM_ATOMIC_H_ */
> --
> 2.1.3
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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