[PATCH 01/10] drm/atomic: Add __drm_atomic_helper_plane_reset

[p.zabel@pengutronix.de (Philipp Zabel)]

Hi Alexandru,

On Fri, 2018-07-20 at 22:15 +0100, Alexandru Gheorghe wrote:
> There are a lot of drivers that subclass drm_plane_state, all of them
> duplicate the code that links toghether the plane with plane_state.
> 
> On top of that, drivers that enable core properties also have to
> duplicate the code for initializing the properties to their default
> values, which in all cases are the same as the defaults from core.
> 
> Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
> ---
>  drivers/gpu/drm/drm_atomic_helper.c | 32 +++++++++++++++++++++--------
>  include/drm/drm_atomic_helper.h     |  2 ++
>  2 files changed, 25 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 8008a7de2e10..e1c6f101652e 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -3507,6 +3507,28 @@ void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
>  }
>  EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state);
>  
> +/**
> + * __drm_atomic_helper_plane_reset - resets planes state to default values
> + * @plane: plane object
> + * @new_state: atomic plane state
> + *
> + * Initializes plane state to default. This is useful for drivers that subclass
> + * the plane state.
> + */
> +void __drm_atomic_helper_plane_reset(struct drm_plane *plane,
> +				     struct drm_plane_state *state)
> +{
> +	if (state) {
> +		state->plane = plane;
> +		state->rotation = DRM_MODE_ROTATE_0;
> +		/* Reset the alpha value to fully opaque if it matters */
> +		if (plane->alpha_property)
> +			state->alpha = plane->alpha_property->values[1];
> +	}

Is this function supposed to be callable with state == NULL ?

> +	plane->state = state;

If so, the comment could mention that this sets plane->state to NULL if
state == NULL, and a few of the call sites could be simplified.

If not, I would remove the conditional if (state) {} part and also
mention this in the comment.

regards
Philipp