Re: [PATCH 1/2] of: Create platform devices for OF framebuffers

[Javier Martinez Canillas <javierm@redhat.com>]

Hello Thomas,

Thanks for working on this.

On 4/13/22 11:24, Thomas Zimmermann wrote:
> Create a platform device for each OF-declared framebuffer and have
> offb bind to these devices. Allows for real hot-unplugging and other
> drivers besides offb.
> 
> Originally, offb created framebuffer devices while initializing its
> module by parsing the OF device tree. No actual Linux device was set
> up. This tied OF framebuffers to offb and makes writing other drivers
> for the OF framebuffers complicated. The absence of a Linux device
> prevented real hot-unplugging. Adding a distinct platform device for
> each OF framebuffer solves both problems. Specifically, a DRM drivers
> can now provide graphics output with modern userspace.
> 
> Some of the offb init code is now located in the OF initialization.
> There's now also an implementation of of_platform_default_populate_init(),
> which was missing before. The OF side creates different devices for
> either OF display nodes or bootx displays as they require different
> handling by the driver. The offb drivers picks up each type of device
> and runs the appropriate fbdev initialization.
> 
> Tested with OF display nodes on qemu's ppc64le target.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---

[snip]

> +	for_each_node_by_type(node, "display") {
> +		if (!of_get_property(node, "linux,opened", NULL) ||
> +		    !of_get_property(node, "linux,boot-display", NULL))
> +			continue;
> +		dev = of_platform_device_create(node, "of-display", NULL);
> +		if (WARN_ON(!dev))
> +			return -ENOMEM;
> +		boot_display = node;
> +		break;
> +	}
> +	for_each_node_by_type(node, "display") {
> +		if (!of_get_property(node, "linux,opened", NULL) || node == boot_display)
> +			continue;
> +		of_platform_device_create(node, "of-display", NULL);

Shouldn't check for the return value here too ?

Other than this small nit, it looks good to me.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Linux Engineering
Red Hat