Re: [PATCH v3 07/11] drm/atomic: Add drm_atomic_can_create_state() helper

[Thomas Zimmermann]

Hi

Am 08.09.26 um 16:35 schrieb Maxime Ripard:
> The atomic reset path will need to create pristine default states from
> scratch for every plane, CRTC, and connector. This requires all of them
> to implement the atomic_create_state hook.
>
> Introduce a drm_atomic_can_create_state() helper that iterates over all
> planes, CRTCs, and connectors and returns whether they all provide the
> hook. Color operations are excluded since they always use
> drm_atomic_helper_colorop_create_state() directly.
>
> This will be used both as a precondition before filling a commit with
> default states, and to report the device capability to userspace.
>
> Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
> ---
>   drivers/gpu/drm/drm_atomic.c | 49 ++++++++++++++++++++++++++++++++++++++++++++
>   include/drm/drm_atomic.h     |  2 ++
>   2 files changed, 51 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 19678e8a2bd4..508a027398af 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -1612,10 +1612,59 @@ drm_atomic_get_new_bridge_state(const struct drm_atomic_commit *state,
>   
>   	return drm_priv_to_bridge_state(obj_state);
>   }
>   EXPORT_SYMBOL(drm_atomic_get_new_bridge_state);
>   
> +/**
> + * drm_atomic_can_create_state - check if a device supports creating pristine states
> + * @dev: DRM device

I find this name a bit vague, because all mode-setting pipelines can 
create states in one way or another. Given how it is used, I suggest 
naming this helper _can_create_default_states or _can_reset_state.

Best regards
Thomas

> + *
> + * Check whether every plane, CRTC, and connector in @dev implements the
> + * &drm_plane_funcs.atomic_create_state, &drm_crtc_funcs.atomic_create_state,
> + * and &drm_connector_funcs.atomic_create_state hooks respectively. These hooks
> + * are required to create default states from scratch rather than duplicating
> + * the current state.
> + *
> + * Color operations are not checked because they always use
> + * drm_atomic_helper_colorop_create_state() and do not have a per-driver hook.
> + *
> + * Returns:
> + * True if all objects implement atomic_create_state, false otherwise.
> + */
> +bool drm_atomic_can_create_state(struct drm_device *dev)
> +{
> +	struct drm_connector_list_iter conn_iter;
> +	struct drm_connector *connector;
> +	struct drm_plane *plane;
> +	struct drm_crtc *crtc;
> +
> +	/*
> +	 * colorops don't have an atomic_create_state hook but
> +	 * drm_atomic_helper_colorop_create_state()
> +	 */
> +
> +	drm_for_each_plane(plane, dev)
> +		if (!plane->funcs->atomic_create_state)
> +			return false;
> +
> +	drm_for_each_crtc(crtc, dev)
> +		if (!crtc->funcs->atomic_create_state)
> +			return false;
> +
> +	drm_connector_list_iter_begin(dev, &conn_iter);
> +	drm_for_each_connector_iter(connector, &conn_iter) {
> +		if (!connector->funcs->atomic_create_state) {
> +			drm_connector_list_iter_end(&conn_iter);
> +			return false;
> +		}
> +	}
> +	drm_connector_list_iter_end(&conn_iter);
> +
> +	return true;
> +}
> +EXPORT_SYMBOL(drm_atomic_can_create_state);
> +
>   /**
>    * drm_atomic_add_encoder_bridges - add bridges attached to an encoder
>    * @state: atomic state
>    * @encoder: DRM encoder
>    *
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index 00b3e9fc429a..7dc26e3da65c 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -700,10 +700,12 @@ int drm_crtc_commit_wait(struct drm_crtc_commit *commit);
>   
>   struct drm_atomic_commit * __must_check
>   drm_atomic_commit_alloc(struct drm_device *dev);
>   void drm_atomic_commit_clear(struct drm_atomic_commit *state);
>   
> +bool drm_atomic_can_create_state(struct drm_device *dev);
> +
>   /**
>    * drm_atomic_commit_get - acquire a reference to the atomic state
>    * @state: The atomic state
>    *
>    * Returns a new reference to the @state

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)