linux-kernel - Re: [PATCH v4 2/9] drm/bridge: simple-bridge: Use fwnode API to acquire device properties

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Message-ID: <7xlzd62dvwjjv6zwbgjwphcgwpjpfxbv5rp243a2duobrpcvmd@gtr6cnm7ndrl>
Date: Mon, 22 Apr 2024 22:56:21 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Sui Jingfeng <sui.jingfeng@...ux.dev>
Cc: Neil Armstrong <neil.armstrong@...aro.org>, 
	Robert Foss <rfoss@...nel.org>, Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
	Andrzej Hajda <andrzej.hajda@...el.com>, Jonas Karlman <jonas@...boo.se>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Daniel Vetter <daniel@...ll.ch>, Phong LE <ple@...libre.com>, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/9] drm/bridge: simple-bridge: Use fwnode API to
 acquire device properties

On Tue, Apr 23, 2024 at 03:18:56AM +0800, Sui Jingfeng wrote:
> Make this driver less DT-dependent by calling the freshly created helpers,
> should be no functional changes for DT based systems. But open the door for
> otherwise use cases. Even though there is no user emerged yet, this still
> do no harms.
> 
> Signed-off-by: Sui Jingfeng <sui.jingfeng@...ux.dev>
> ---
>  drivers/gpu/drm/bridge/simple-bridge.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/simple-bridge.c b/drivers/gpu/drm/bridge/simple-bridge.c
> index 5813a2c4fc5e..3b09bdd5ad4d 100644
> --- a/drivers/gpu/drm/bridge/simple-bridge.c
> +++ b/drivers/gpu/drm/bridge/simple-bridge.c
> @@ -9,7 +9,6 @@
>  #include <linux/gpio/consumer.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> -#include <linux/of_graph.h>
>  #include <linux/platform_device.h>
>  #include <linux/regulator/consumer.h>
>  
> @@ -169,33 +168,32 @@ static const struct drm_bridge_funcs simple_bridge_bridge_funcs = {
>  
>  static int simple_bridge_probe(struct platform_device *pdev)
>  {
> +	struct fwnode_handle *fwnode = dev_fwnode(&pdev->dev);
>  	struct simple_bridge *sbridge;
> -	struct device_node *remote;
> +	int ret;
>  
>  	sbridge = devm_kzalloc(&pdev->dev, sizeof(*sbridge), GFP_KERNEL);
>  	if (!sbridge)
>  		return -ENOMEM;
>  	platform_set_drvdata(pdev, sbridge);
>  
> -	sbridge->info = of_device_get_match_data(&pdev->dev);
> +	sbridge->info = device_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);
> -
> +	sbridge->next_bridge = drm_bridge_find_next_bridge_by_fwnode(fwnode, 1);

Can we please stick to the interface of drm_of_find_panel_or_bridge()?

Also note, the driver isn't looking for the next_bridge. It is looking
for the bridge at the fwnode remote endpoint.

>  	if (!sbridge->next_bridge) {
>  		dev_dbg(&pdev->dev, "Next bridge not found, deferring probe\n");
>  		return -EPROBE_DEFER;
> +	} else if (IS_ERR(sbridge->next_bridge)) {
> +		ret = PTR_ERR(sbridge->next_bridge);
> +		dev_err(&pdev->dev, "Error on finding the next bridge: %d\n", ret);
> +		return ret;
>  	}
>  
>  	/* Get the regulator and GPIO resources. */
>  	sbridge->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
>  	if (IS_ERR(sbridge->vdd)) {
> -		int ret = PTR_ERR(sbridge->vdd);
> +		ret = PTR_ERR(sbridge->vdd);
>  		if (ret == -EPROBE_DEFER)
>  			return -EPROBE_DEFER;
>  		sbridge->vdd = NULL;
> @@ -210,9 +208,9 @@ 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.timings = sbridge->info->timings;
>  
> +	drm_bridge_set_node(&sbridge->bridge, fwnode);

Please don't move the code. Having it in place of of_node setter
simplifies the review.

LGTM otherwise.

>  	drm_bridge_add(&sbridge->bridge);
>  
>  	return 0;
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry