linux-kernel - Re: [PATCH v2 01/28] drm: Introduce drm_bridge

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Message-ID: <20191204131015.GM624164@phenom.ffwll.local>
Date:   Wed, 4 Dec 2019 14:10:15 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Mihail Atanassov <Mihail.Atanassov@....com>
Cc:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        nd <nd@....com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 01/28] drm: Introduce drm_bridge_init()

On Wed, Dec 04, 2019 at 11:48:02AM +0000, Mihail Atanassov wrote:
> A simple convenience function to initialize the struct drm_bridge. The
> goal is to standardize initialization for any bridge registered with
> drm_bridge_add() so that we can later add device links for consumers of
> those bridges.
> 
> v2:
>  - s/WARN_ON(!funcs)/WARN_ON(!funcs || !dev)/ as suggested by Daniel
>  - expand on some kerneldoc comments as suggested by Daniel
>  - update commit message as suggested by Daniel
> 
> Signed-off-by: Mihail Atanassov <mihail.atanassov@....com>

Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>

> ---
>  drivers/gpu/drm/drm_bridge.c | 34 +++++++++++++++++++++++++++++++++-
>  include/drm/drm_bridge.h     | 15 ++++++++++++++-
>  2 files changed, 47 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index cba537c99e43..50e1c1b46e20 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -64,7 +64,10 @@ static DEFINE_MUTEX(bridge_lock);
>  static LIST_HEAD(bridge_list);
>  
>  /**
> - * drm_bridge_add - add the given bridge to the global bridge list
> + * drm_bridge_add - add the given bridge to the global bridge list.
> + *
> + * Drivers should call drm_bridge_init() prior adding it to the list.
> + * Drivers should call drm_bridge_remove() to clean up the bridge list.
>   *
>   * @bridge: bridge control structure
>   */
> @@ -89,6 +92,35 @@ void drm_bridge_remove(struct drm_bridge *bridge)
>  }
>  EXPORT_SYMBOL(drm_bridge_remove);
>  
> +/**
> + * drm_bridge_init - initialise a drm_bridge structure
> + *
> + * @bridge: bridge control structure
> + * @funcs: control functions
> + * @dev: device associated with this drm_bridge
> + * @timings: timing specification for the bridge; optional (may be NULL)
> + * @driver_private: pointer to the bridge driver internal context (may be NULL)
> + */
> +void drm_bridge_init(struct drm_bridge *bridge, struct device *dev,
> +		     const struct drm_bridge_funcs *funcs,
> +		     const struct drm_bridge_timings *timings,
> +		     void *driver_private)
> +{
> +	WARN_ON(!funcs || !dev);
> +
> +	bridge->dev = NULL;
> +	bridge->encoder = NULL;
> +	bridge->next = NULL;
> +
> +#ifdef CONFIG_OF
> +	bridge->of_node = dev->of_node;
> +#endif
> +	bridge->timings = timings;
> +	bridge->funcs = funcs;
> +	bridge->driver_private = driver_private;
> +}
> +EXPORT_SYMBOL(drm_bridge_init);
> +
>  /**
>   * drm_bridge_attach - attach the bridge to an encoder's chain
>   *
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index c0a2286a81e9..949e4f401a53 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -373,7 +373,16 @@ struct drm_bridge_timings {
>  };
>  
>  /**
> - * struct drm_bridge - central DRM bridge control structure
> + * struct drm_bridge - central DRM bridge control structure.
> + *
> + * Bridge drivers should call drm_bridge_init() to initialize a bridge
> + * driver, and then register it with drm_bridge_add().
> + *
> + * Users of bridges link a bridge driver into their overall display output
> + * pipeline by calling drm_bridge_attach().
> + *
> + * Modular drivers in OF systems can query the list of registered bridges
> + * with of_drm_find_bridge().
>   */
>  struct drm_bridge {
>  	/** @dev: DRM device this bridge belongs to */
> @@ -402,6 +411,10 @@ struct drm_bridge {
>  
>  void drm_bridge_add(struct drm_bridge *bridge);
>  void drm_bridge_remove(struct drm_bridge *bridge);
> +void drm_bridge_init(struct drm_bridge *bridge, struct device *dev,
> +		     const struct drm_bridge_funcs *funcs,
> +		     const struct drm_bridge_timings *timings,
> +		     void *driver_private);
>  struct drm_bridge *of_drm_find_bridge(struct device_node *np);
>  int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
>  		      struct drm_bridge *previous);
> -- 
> 2.23.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch