Re: [PATCH v4 2/5] drm/atomic: Make drm_atomic_plane_disabling easier to understand.

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Maarten,

Thank you for the patch.

On Thursday 16 Feb 2017 15:47:07 Maarten Lankhorst wrote:
> This function becomes a lot simpler when having passed both the old and
> new state to it. Looking at all callers, it seems that old_plane_state
> is never NULL so the check can be dropped.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/gpu/drm/drm_atomic_helper.c |  7 ++++---
>  drivers/gpu/drm/drm_plane_helper.c  |  2 +-
>  include/drm/drm_atomic_helper.h     | 26 ++++++++------------------
>  3 files changed, 13 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> b/drivers/gpu/drm/drm_atomic_helper.c index 7d432d9a18cf..ea544bddc29b
> 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -1757,7 +1757,8 @@ void drm_atomic_helper_commit_planes(struct drm_device
> *dev, if (!funcs)
>  			continue;
> 
> -		disabling = drm_atomic_plane_disabling(plane, 
old_plane_state);
> +		disabling = drm_atomic_plane_disabling(old_plane_state,
> +						       new_plane_state);
> 
>  		if (active_only) {
>  			/*
> @@ -1852,11 +1853,11 @@ drm_atomic_helper_commit_planes_on_crtc(struct
> drm_crtc_state *old_crtc_state)
> 
>  		WARN_ON(plane->state->crtc && plane->state->crtc != crtc);
> 
> -		if (drm_atomic_plane_disabling(plane, old_plane_state) &&
> +		if (drm_atomic_plane_disabling(old_plane_state, plane->state) 
&&
>  		    plane_funcs->atomic_disable)
>  			plane_funcs->atomic_disable(plane, old_plane_state);
>  		else if (plane->state->crtc ||
> -			 drm_atomic_plane_disabling(plane, old_plane_state))
> +			 drm_atomic_plane_disabling(old_plane_state, plane-
>state))
>  			plane_funcs->atomic_update(plane, old_plane_state);
>  	}
> 
> diff --git a/drivers/gpu/drm/drm_plane_helper.c
> b/drivers/gpu/drm/drm_plane_helper.c index 148688fb920a..f4d70dd5e3e4
> 100644
> --- a/drivers/gpu/drm/drm_plane_helper.c
> +++ b/drivers/gpu/drm/drm_plane_helper.c
> @@ -470,7 +470,7 @@ int drm_plane_helper_commit(struct drm_plane *plane,
>  	 * Drivers may optionally implement the ->atomic_disable callback, so
>  	 * special-case that here.
>  	 */
> -	if (drm_atomic_plane_disabling(plane, plane_state) &&
> +	if (drm_atomic_plane_disabling(plane_state, plane->state) &&
>  	    plane_funcs->atomic_disable)
>  		plane_funcs->atomic_disable(plane, plane_state);
>  	else
> diff --git a/include/drm/drm_atomic_helper.h
> b/include/drm/drm_atomic_helper.h index 9ceda379ce58..dc16274987c7 100644
> --- a/include/drm/drm_atomic_helper.h
> +++ b/include/drm/drm_atomic_helper.h
> @@ -220,10 +220,10 @@ int drm_atomic_helper_legacy_gamma_set(struct drm_crtc
> *crtc, __drm_atomic_get_current_plane_state((crtc_state)->state, \ plane)))
> 
> -/*
> +/**
>   * drm_atomic_plane_disabling - check whether a plane is being disabled
> - * @plane: plane object
> - * @old_state: previous atomic state
> + * @old_plane_state: old atomic plane state
> + * @new_plane_state: new atomic plane state
>   *
>   * Checks the atomic state of a plane to determine whether it's being
> disabled * or not. This also WARNs if it detects an invalid state (both
> CRTC and FB @@ -233,28 +233,18 @@ int
> drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc, * True if the
> plane is being disabled, false otherwise.
>   */
>  static inline bool
> -drm_atomic_plane_disabling(struct drm_plane *plane,
> -			   struct drm_plane_state *old_state)
> +drm_atomic_plane_disabling(struct drm_plane_state *old_plane_state,
> +			   struct drm_plane_state *new_plane_state)
>  {
>  	/*
>  	 * When disabling a plane, CRTC and FB should always be NULL together.
>  	 * Anything else should be considered a bug in the atomic core, so we
>  	 * gently warn about it.
>  	 */
> -	WARN_ON((plane->state->crtc == NULL && plane->state->fb != NULL) ||
> -		(plane->state->crtc != NULL && plane->state->fb == NULL));
> +	WARN_ON((new_plane_state->crtc == NULL && new_plane_state->fb != NULL) 
||
> +		(new_plane_state->crtc != NULL && new_plane_state->fb == 
NULL));
> 
> -	/*
> -	 * When using the transitional helpers, old_state may be NULL. If so,
> -	 * we know nothing about the current state and have to assume that it
> -	 * might be enabled.
> -	 *
> -	 * When using the atomic helpers, old_state won't be NULL. Therefore
> -	 * this check assumes that either the driver will have reconstructed
> -	 * the correct state in ->reset() or that the driver will have taken
> -	 * appropriate measures to disable all planes.
> -	 */
> -	return (!old_state || old_state->crtc) && !plane->state->crtc;
> +	return old_plane_state->crtc && !new_plane_state->crtc;
>  }
> 
>  #endif /* DRM_ATOMIC_HELPER_H_ */

-- 
Regards,

Laurent Pinchart

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