[PATCH] drm/atomic: Add new reverse iterator over all plane state (V2)

[Harry Wentland]

On 2018-03-06 10:10 PM, Shirish S wrote:
> Add reverse iterator for_each_oldnew_plane_in_state_reverse to
> compliment the for_each_oldnew_plane_in_state way or reading plane
> states.
> 
> The plane states are required to be read in reverse order for
> amd drivers, cause the z order convention followed in linux is
> opposite to how the planes are supposed to be presented to DC
> engine, which is in common to both windows and linux.
> 
> V2: fix compile time errors due to -Werror flag.
> 
> Signed-off-by: Shirish S <shirish.s at amd.com>
> Signed-off-by: Pratik Vishwakarma <Pratik.Vishwakarma at amd.com>
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Merged to drm-misc-next.

Harry

> ---
>  include/drm/drm_atomic.h | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index cf13842..3fe8dde 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -754,6 +754,28 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
>  			      (new_plane_state) = (__state)->planes[__i].new_state, 1))
>  
>  /**
> + * for_each_oldnew_plane_in_state_reverse - iterate over all planes in an atomic
> + * update in reverse order
> + * @__state: &struct drm_atomic_state pointer
> + * @plane: &struct drm_plane iteration cursor
> + * @old_plane_state: &struct drm_plane_state iteration cursor for the old state
> + * @new_plane_state: &struct drm_plane_state iteration cursor for the new state
> + * @__i: int iteration cursor, for macro-internal use
> + *
> + * This iterates over all planes in an atomic update in reverse order,
> + * tracking both old and  new state. This is useful in places where the
> + * state delta needs to be considered, for example in atomic check functions.
> + */
> +#define for_each_oldnew_plane_in_state_reverse(__state, plane, old_plane_state, new_plane_state, __i) \
> +	for ((__i) = ((__state)->dev->mode_config.num_total_plane - 1);	\
> +	     (__i) >= 0;						\
> +	     (__i)--)							\
> +		for_each_if ((__state)->planes[__i].ptr &&		\
> +			     ((plane) = (__state)->planes[__i].ptr,	\
> +			      (old_plane_state) = (__state)->planes[__i].old_state,\
> +			      (new_plane_state) = (__state)->planes[__i].new_state, 1))
> +
> +/**
>   * for_each_old_plane_in_state - iterate over all planes in an atomic update
>   * @__state: &struct drm_atomic_state pointer
>   * @plane: &struct drm_plane iteration cursor
>