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Date:   Fri, 15 Jan 2021 23:20:21 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Maxime Ripard <maxime@cerno.tech>
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Subject: Re: [PATCH 10/10] drm: Use state helper instead of the plane state
 pointer
Message-ID: <YAIHFTYiry6ebUsY@pendragon.ideasonboard.com>
References: <20210115125703.1315064-1-maxime@cerno.tech>
 <20210115125703.1315064-10-maxime@cerno.tech>
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In-Reply-To: <20210115125703.1315064-10-maxime@cerno.tech>
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Hi Maxime,

Thank you for the patch.

On Fri, Jan 15, 2021 at 01:57:02PM +0100, Maxime Ripard wrote:
> Many drivers reference the plane->state pointer in order to get the
> current plane state in their atomic_update or atomic_disable hooks,

Please don't use the word "current", it's ambiguous. Do you mean old
state or new state ?

> which would be the new plane state in the global atomic state since
> _swap_state happened when those hooks are run.

Is this relevant ? drm_atomic_helper_swap_state() doesn't change the
old_state and new_state pointers in drm_atomic_state as far as I can
tell.

> Use the drm_atomic_get_new_plane_state helper to get that state to make it
> more obvious.
> 
> This was made using the coccinelle script below:
> 
> @ plane_atomic_func @
> identifier helpers;
> identifier func;
> @@
> 
> (
>  static const struct drm_plane_helper_funcs helpers = {
>  	...,
>  	.atomic_disable = func,
> 	...,
>  };
> |
>  static const struct drm_plane_helper_funcs helpers = {
>  	...,
>  	.atomic_update = func,
> 	...,
>  };
> )
> 
> @ adds_new_state @
> identifier plane_atomic_func.func;
> identifier plane, state;
> identifier new_state;
> @@
> 
>  func(struct drm_plane *plane, struct drm_atomic_state *state)
>  {
>  	...
> -	struct drm_plane_state *new_state = plane->state;
> +	struct drm_plane_state *new_state = drm_atomic_get_new_plane_state(state, plane);
> 	...
>  }
> 
> @ include depends on adds_new_state @
> @@
> 
>  #include <drm/drm_atomic.h>
> 
> @ no_include depends on !include && adds_new_state @
> @@
> 
> + #include <drm/drm_atomic.h>
>   #include <drm/...>
> 
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> ---

[snip]

>  drivers/gpu/drm/omapdrm/omap_plane.c            | 6 ++++--
>  drivers/gpu/drm/rcar-du/rcar_du_plane.c         | 3 ++-
>  drivers/gpu/drm/rcar-du/rcar_du_vsp.c           | 3 ++-
>  drivers/gpu/drm/xlnx/zynqmp_disp.c              | 3 ++-

[snip]

> diff --git a/drivers/gpu/drm/omapdrm/omap_plane.c b/drivers/gpu/drm/omapdrm/omap_plane.c
> index cd8cf7c786b5..021a94de84a1 100644
> --- a/drivers/gpu/drm/omapdrm/omap_plane.c
> +++ b/drivers/gpu/drm/omapdrm/omap_plane.c
> @@ -44,7 +44,8 @@ static void omap_plane_atomic_update(struct drm_plane *plane,
>  {
>  	struct omap_drm_private *priv = plane->dev->dev_private;
>  	struct omap_plane *omap_plane = to_omap_plane(plane);
> -	struct drm_plane_state *new_state = plane->state;

This seems to imply that you're interested in the new state.

> +	struct drm_plane_state *new_state = drm_atomic_get_new_plane_state(state,
> +									   plane);

Does this really make things more obvious ?

>  	struct omap_overlay_info info;
>  	int ret;
>  
> @@ -89,7 +90,8 @@ static void omap_plane_atomic_update(struct drm_plane *plane,
>  static void omap_plane_atomic_disable(struct drm_plane *plane,
>  				      struct drm_atomic_state *state)
>  {
> -	struct drm_plane_state *new_state = plane->state;
> +	struct drm_plane_state *new_state = drm_atomic_get_new_plane_state(state,
> +									   plane);
>  	struct omap_drm_private *priv = plane->dev->dev_private;
>  	struct omap_plane *omap_plane = to_omap_plane(plane);
>  

[snip]

-- 
Regards,

Laurent Pinchart