Re: [PATCH v2 3/4] drm/atomic: Add macros to access existing old/new state

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Nov 16, 2016 at 02:58:07PM +0100, Maarten Lankhorst wrote:
> During atomic check/commit, these macros should be used in place of
> get_existing_state.
> 
> We also ban the use of get_xx_state after atomic check, because at that
> point no new locks should be taken and get_new/old_state should be used
> instead.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

So one slightly annoying thing with the new/old split is that const-ness
of these changes. In atomic_check the old state should be const, in
atomic_commit the new state. By going to the new/old split we're losing
that safeguard. Otoh we have lots and lots of exceptions to that rule ...
not sure how much aiming for const correctness is worth it.
-Daniel

> ---
>  include/drm/drm_atomic.h | 100 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 100 insertions(+)
> 
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index 462408a2d1b8..7be178264732 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -264,6 +264,36 @@ drm_atomic_get_existing_crtc_state(struct drm_atomic_state *state,
>  }
>  
>  /**
> + * drm_atomic_get_old_crtc_state - get old crtc state, if it exists
> + * @state: global atomic state object
> + * @crtc: crtc to grab
> + *
> + * This function returns the old crtc state for the given crtc, or
> + * NULL if the crtc is not part of the global atomic state.
> + */
> +static inline struct drm_crtc_state *
> +drm_atomic_get_old_crtc_state(struct drm_atomic_state *state,
> +			      struct drm_crtc *crtc)
> +{
> +	return state->crtcs[drm_crtc_index(crtc)].old_state;
> +}
> +
> +/**
> + * drm_atomic_get_new_crtc_state - get new crtc state, if it exists
> + * @state: global atomic state object
> + * @crtc: crtc to grab
> + *
> + * This function returns the new crtc state for the given crtc, or
> + * NULL if the crtc is not part of the global atomic state.
> + */
> +static inline struct drm_crtc_state *
> +drm_atomic_get_new_crtc_state(struct drm_atomic_state *state,
> +			      struct drm_crtc *crtc)
> +{
> +	return state->crtcs[drm_crtc_index(crtc)].new_state;
> +}
> +
> +/**
>   * drm_atomic_get_existing_plane_state - get plane state, if it exists
>   * @state: global atomic state object
>   * @plane: plane to grab
> @@ -279,6 +309,36 @@ drm_atomic_get_existing_plane_state(struct drm_atomic_state *state,
>  }
>  
>  /**
> + * drm_atomic_get_old_plane_state - get plane state, if it exists
> + * @state: global atomic state object
> + * @plane: plane to grab
> + *
> + * This function returns the old plane state for the given plane, or
> + * NULL if the plane is not part of the global atomic state.
> + */
> +static inline struct drm_plane_state *
> +drm_atomic_get_old_plane_state(struct drm_atomic_state *state,
> +			       struct drm_plane *plane)
> +{
> +	return state->planes[drm_plane_index(plane)].old_state;
> +}
> +
> +/**
> + * drm_atomic_get_new_plane_state - get plane state, if it exists
> + * @state: global atomic state object
> + * @plane: plane to grab
> + *
> + * This function returns the new plane state for the given plane, or
> + * NULL if the plane is not part of the global atomic state.
> + */
> +static inline struct drm_plane_state *
> +drm_atomic_get_new_plane_state(struct drm_atomic_state *state,
> +			       struct drm_plane *plane)
> +{
> +	return state->planes[drm_plane_index(plane)].new_state;
> +}
> +
> +/**
>   * drm_atomic_get_existing_connector_state - get connector state, if it exists
>   * @state: global atomic state object
>   * @connector: connector to grab
> @@ -299,6 +359,46 @@ drm_atomic_get_existing_connector_state(struct drm_atomic_state *state,
>  }
>  
>  /**
> + * drm_atomic_get_old_connector_state - get connector state, if it exists
> + * @state: global atomic state object
> + * @connector: connector to grab
> + *
> + * This function returns the old connector state for the given connector,
> + * or NULL if the connector is not part of the global atomic state.
> + */
> +static inline struct drm_connector_state *
> +drm_atomic_get_old_connector_state(struct drm_atomic_state *state,
> +				   struct drm_connector *connector)
> +{
> +	int index = drm_connector_index(connector);
> +
> +	if (index >= state->num_connector)
> +		return NULL;
> +
> +	return state->connectors[index].old_state;
> +}
> +
> +/**
> + * drm_atomic_get_new_connector_state - get connector state, if it exists
> + * @state: global atomic state object
> + * @connector: connector to grab
> + *
> + * This function returns the new connector state for the given connector,
> + * or NULL if the connector is not part of the global atomic state.
> + */
> +static inline struct drm_connector_state *
> +drm_atomic_get_new_connector_state(struct drm_atomic_state *state,
> +				   struct drm_connector *connector)
> +{
> +	int index = drm_connector_index(connector);
> +
> +	if (index >= state->num_connector)
> +		return NULL;
> +
> +	return state->connectors[index].new_state;
> +}
> +
> +/**
>   * __drm_atomic_get_current_plane_state - get current plane state
>   * @state: global atomic state object
>   * @plane: plane to grab
> -- 
> 2.7.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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