linux-kernel - Re: [PATCH 3/5] drm/bridge: simple-bridge: Allow acquiring the next bridge with fwnode API

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Message-ID: <20240123011859.GB22880@pendragon.ideasonboard.com>
Date: Tue, 23 Jan 2024 03:18:59 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Sui Jingfeng <sui.jingfeng@...ux.dev>
Cc: David Airlie <airlied@...il.com>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Daniel Vetter <daniel@...ll.ch>, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] drm/bridge: simple-bridge: Allow acquiring the next
 bridge with fwnode API

On Tue, Jan 23, 2024 at 12:32:18AM +0800, Sui Jingfeng wrote:
> Which make it possible to use this driver on non-DT based systems,
> meanwhile, made no functional changes for DT based systems.
> 
> Signed-off-by: Sui Jingfeng <sui.jingfeng@...ux.dev>
> ---
>  drivers/gpu/drm/bridge/simple-bridge.c | 51 ++++++++++++++++++++++----
>  1 file changed, 44 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/simple-bridge.c b/drivers/gpu/drm/bridge/simple-bridge.c
> index 595f672745b9..cfea5a67cc5b 100644
> --- a/drivers/gpu/drm/bridge/simple-bridge.c
> +++ b/drivers/gpu/drm/bridge/simple-bridge.c
> @@ -184,6 +184,39 @@ static const void *simple_bridge_get_match_data(const struct device *dev)
>  	return NULL;
>  }
>  
> +static int simple_bridge_get_next_bridge_by_fwnode(struct device *dev,
> +						   struct drm_bridge **next_bridge)
> +{
> +	struct drm_bridge *bridge;
> +	struct fwnode_handle *ep;
> +	struct fwnode_handle *remote;
> +
> +	ep = fwnode_graph_get_endpoint_by_id(dev->fwnode, 1, 0, 0);
> +	if (!ep) {
> +		dev_err(dev, "The endpoint is unconnected\n");
> +		return -EINVAL;
> +	}
> +
> +	remote = fwnode_graph_get_remote_port_parent(ep);
> +	fwnode_handle_put(ep);
> +	if (!remote) {
> +		dev_err(dev, "No valid remote node\n");
> +		return -ENODEV;
> +	}
> +
> +	bridge = drm_bridge_find_by_fwnode(remote);
> +	fwnode_handle_put(remote);
> +
> +	if (!bridge) {
> +		dev_warn(dev, "Next bridge not found, deferring probe\n");
> +		return -EPROBE_DEFER;
> +	}
> +
> +	*next_bridge = bridge;
> +
> +	return 0;
> +}
> +

Hmmmm yes, this convinces me further that we should switch to fwnode,
not implement fwnode and OF side-by-side.

>  static int simple_bridge_probe(struct platform_device *pdev)
>  {
>  	struct simple_bridge *sbridge;
> @@ -199,14 +232,17 @@ static int simple_bridge_probe(struct platform_device *pdev)
>  	else
>  		sbridge->info = simple_bridge_get_match_data(&pdev->dev);
>  
> -	/* Get the next bridge in the pipeline. */
> -	remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
> -	if (!remote)
> -		return -EINVAL;
> -
> -	sbridge->next_bridge = of_drm_find_bridge(remote);
> -	of_node_put(remote);
> +	if (pdev->dev.of_node) {
> +		/* Get the next bridge in the pipeline. */
> +		remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
> +		if (!remote)
> +			return -EINVAL;
>  
> +		sbridge->next_bridge = of_drm_find_bridge(remote);
> +		of_node_put(remote);
> +	} else {
> +		simple_bridge_get_next_bridge_by_fwnode(&pdev->dev, &sbridge->next_bridge);
> +	}
>  	if (!sbridge->next_bridge) {
>  		dev_dbg(&pdev->dev, "Next bridge not found, deferring probe\n");
>  		return -EPROBE_DEFER;
> @@ -231,6 +267,7 @@ static int simple_bridge_probe(struct platform_device *pdev)
>  	/* Register the bridge. */
>  	sbridge->bridge.funcs = &simple_bridge_bridge_funcs;
>  	sbridge->bridge.of_node = pdev->dev.of_node;
> +	sbridge->bridge.fwnode = pdev->dev.fwnode;
>  	sbridge->bridge.timings = sbridge->info->timings;
>  
>  	drm_bridge_add(&sbridge->bridge);
> -- 
> 2.25.1
> 

-- 
Regards,

Laurent Pinchart