linux-kernel - Re: [PATCH 1/3] drm/simpledrm: Bind to OF framebuffers in /chosen

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Date:   Sat, 20 Nov 2021 12:23:58 +0900
From:   Hector Martin <marcan@...can.st>
To:     Thomas Zimmermann <tzimmermann@...e.de>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>
Cc:     dri-devel@...ts.freedesktop.org,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 1/3] drm/simpledrm: Bind to OF framebuffers in /chosen

On 18/11/2021 18.19, Thomas Zimmermann wrote:
> Hi
> 
> Am 17.11.21 um 15:58 schrieb Hector Martin:
>> @@ -897,5 +898,21 @@ static struct platform_driver simpledrm_platform_driver = {
>>    
>>    module_platform_driver(simpledrm_platform_driver);
>>    
>> +static int __init simpledrm_init(void)
>> +{
>> +	struct device_node *np;
>> +
>> +	if (IS_ENABLED(CONFIG_OF_ADDRESS) && of_chosen) {
>> +		for_each_child_of_node(of_chosen, np) {
>> +			if (of_device_is_compatible(np, "simple-framebuffer"))
>> +				of_platform_device_create(np, NULL, NULL);
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +fs_initcall(simpledrm_init);
>> +
> 
> Simpledrm is just a driver, but this is platform setup code. Why is this
> code located here and not under arch/ or drivers/firmware/?
> 
> I know that other drivers do similar things, it doesn't seem to belong here.

This definitely doesn't belong in either of those, since it is not arch- 
or firmware-specific. It is implementing support for the standard 
simple-framebuffer OF binding, which specifies that it must be located 
within the /chosen node (and thus the default OF setup code won't do the 
matching for you); this applies to all OF platforms [1]

Adding Rob; do you think this should move from simplefb/simpledrm to 
common OF code? (where?)

[1] Documentation/devicetree/bindings/display/simple-framebuffer.yaml

-- 
Hector Martin (marcan@...can.st)
Public Key: https://mrcn.st/pub