linux-kernel - Re: [PATCH] drm: bridge: thc63lvd1024: Switch to use of_graph_get_remote

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Date: Mon, 18 Mar 2024 23:59:29 +0800
From: Sui Jingfeng <sui.jingfeng@...ux.dev>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm: bridge: thc63lvd1024: Switch to use
 of_graph_get_remote_node()

Hi,


On 2024/3/18 23:57, Laurent Pinchart wrote:
> On Mon, Mar 18, 2024 at 11:53:11PM +0800, Sui Jingfeng wrote:
>> On 2024/3/18 23:33, Laurent Pinchart wrote:
>>> On Sun, Mar 17, 2024 at 01:28:00AM +0800, Sui Jingfeng wrote:
>>>> To reduce boilerplate, use of_graph_get_remote_node() helper instead of
>>>> the hand-rolling code.
>>>>
>>>> Signed-off-by: Sui Jingfeng <sui.jingfeng@...ux.dev>
>>>> ---
>>>>    drivers/gpu/drm/bridge/thc63lvd1024.c | 24 +++---------------------
>>>>    1 file changed, 3 insertions(+), 21 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/bridge/thc63lvd1024.c b/drivers/gpu/drm/bridge/thc63lvd1024.c
>>>> index d4c1a601bbb5..5f99f9724081 100644
>>>> --- a/drivers/gpu/drm/bridge/thc63lvd1024.c
>>>> +++ b/drivers/gpu/drm/bridge/thc63lvd1024.c
>>>> @@ -123,28 +123,10 @@ static int thc63_parse_dt(struct thc63_dev *thc63)
>>>>    	struct device_node *endpoint;
>>>>    	struct device_node *remote;
>>>>    
>>>> -	endpoint = of_graph_get_endpoint_by_regs(thc63->dev->of_node,
>>>> -						 THC63_RGB_OUT0, -1);
>>>> -	if (!endpoint) {
>>>> -		dev_err(thc63->dev, "Missing endpoint in port@%u\n",
>>>> -			THC63_RGB_OUT0);
>>>> -		return -ENODEV;
>>>> -	}
>>>> -
>>>> -	remote = of_graph_get_remote_port_parent(endpoint);
>>>> -	of_node_put(endpoint);
>>>> -	if (!remote) {
>>>> -		dev_err(thc63->dev, "Endpoint in port@%u unconnected\n",
>>>> -			THC63_RGB_OUT0);
>>>> +	remote = of_graph_get_remote_node(thc63->dev->of_node,
>>>> +					  THC63_RGB_OUT0, -1);
>>>> +	if (!remote)
>>> The old logic is equivalent to of_graph_get_remote_node(), but now the
>>> driver will fail probing without an error message. That's not very nice
>>> as it leads to difficult to debug problems. I would keep one dev_err()
>>> here:
>>>
>>> 		dev_err(thc63->dev, "No remote endpoint for port@%u\n",
>>> 			THC63_RGB_OUT0);
>>>
>>> As your patch has been merged already, would you like to post a
>>> follow-up patch to fix this ?
>> Yes, this is indeed a difference. I will post a follow-up patch to fix this.
> I'm actually build-testing a patch I already wrote :-) I'll post it in a
> moment.


OK, then.


>>>>    		return -ENODEV;
>>>> -	}
>>>> -
>>>> -	if (!of_device_is_available(remote)) {
>>>> -		dev_err(thc63->dev, "port@%u remote endpoint is disabled\n",
>>>> -			THC63_RGB_OUT0);
>>>> -		of_node_put(remote);
>>>> -		return -ENODEV;
>>>> -	}
>>>>    
>>>>    	thc63->next = of_drm_find_bridge(remote);
>>>>    	of_node_put(remote);

-- 
Best regards,
Sui