Re: [PATCH v2 2/2] drm/panel: Add device_link from panel device to drm device

[Lukas Wunner <lukas@wunner.de>]

On Wed, Feb 28, 2018 at 01:09:30PM +0200, Jyri Sarha wrote:
> Add device_link from panel device (supplier) to drm device (consumer)
> with DL_FLAG_AUTOREMOVE when drm_panel_attach() is called. Currently
> the master drm driver is not protected against the attached. The
> device_link with DL_FLAG_AUTOREMOVE should make sure the drm device is
> unbound before the panel driver becomes unavailable.
> 
> The device_link is removed when drm_panel_detach() is called. The
> drm_panel_detach() should be called by the panel driver it self when
> it is removed. Otherwise the both driver are racing to delete the same
> link.

AFAICS drm_panel_detach() is always called by the DRM drivers, so it's
confusing that you're saying here it should be called by the panel
drivers.  That would also seem to be asymmetric since drm_panel_attach()
is called by the DRM drivers.


> --- a/include/drm/drm_panel.h
> +++ b/include/drm/drm_panel.h
> @@ -89,6 +89,7 @@ struct drm_panel {
>  	struct drm_device *drm;
>  	struct drm_connector *connector;
>  	struct device *dev;
> +	struct device_link *link;
>  
>  	const struct drm_panel_funcs *funcs;

If you ditch the device_link_del() and use DL_FLAG_AUTOREMOVE only,
you don't need to save the pointer to struct device_link.

Thanks,

Lukas
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