Re: [PATCH] drm: Drop unused drm_device_class_(un)register API

[Tvrtko Ursulin <tvrtko.ursulin@igalia.com>]

On 29/04/2026 10:35, Thomas Zimmermann wrote:
> Hi
> 
> Am 29.04.26 um 10:57 schrieb Tvrtko Ursulin:
>> The API has been unused since commit
>> ed89fff97382 ("drm/ttm: drop sysfs directory")
>> so lets remove it.
> 
> drm_privacy_screen_register() uses the same pattern. [1] If that helper 
> is being converted over to drm_class_device_register(), the global 
> drm_class could be internalized into drm_sysfb.c. Personally, I think 
> this is the better solution, but either seems fine. [1] https:// 
> elixir.bootlin.com/linux/v7.0.1/source/drivers/gpu/drm/ 
> drm_privacy_screen.c#L405

I did not spot that one. The alternative sounds reasonable to me. Adding 
Hans to check if he wants to take over converting this driver.

Regards,

Tvrtko
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
>> Cc: Christian König <christian.koenig@amd.com>
>> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> Cc: Maxime Ripard <mripard@kernel.org>
>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>> Cc: David Airlie <airlied@gmail.com>
>> Cc: Simona Vetter <simona@ffwll.ch>
>> ---
>>   drivers/gpu/drm/drm_sysfs.c | 32 --------------------------------
>>   include/drm/drm_sysfs.h     |  4 ----
>>   2 files changed, 36 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
>> index 43b2c3eaa7e4..7433bf8136cc 100644
>> --- a/drivers/gpu/drm/drm_sysfs.c
>> +++ b/drivers/gpu/drm/drm_sysfs.c
>> @@ -645,35 +645,3 @@ struct device *drm_sysfs_minor_alloc(struct 
>> drm_minor *minor)
>>       put_device(kdev);
>>       return ERR_PTR(r);
>>   }
>> -
>> -/**
>> - * drm_class_device_register - register new device with the DRM sysfs 
>> class
>> - * @dev: device to register
>> - *
>> - * Registers a new &struct device within the DRM sysfs class. 
>> Essentially only
>> - * used by ttm to have a place for its global settings. Drivers 
>> should never use
>> - * this.
>> - */
>> -int drm_class_device_register(struct device *dev)
>> -{
>> -    if (!drm_class || IS_ERR(drm_class))
>> -        return -ENOENT;
>> -
>> -    dev->class = drm_class;
>> -    return device_register(dev);
>> -}
>> -EXPORT_SYMBOL_GPL(drm_class_device_register);
>> -
>> -/**
>> - * drm_class_device_unregister - unregister device with the DRM sysfs 
>> class
>> - * @dev: device to unregister
>> - *
>> - * Unregisters a &struct device from the DRM sysfs class. Essentially 
>> only used
>> - * by ttm to have a place for its global settings. Drivers should 
>> never use
>> - * this.
>> - */
>> -void drm_class_device_unregister(struct device *dev)
>> -{
>> -    return device_unregister(dev);
>> -}
>> -EXPORT_SYMBOL_GPL(drm_class_device_unregister);
>> diff --git a/include/drm/drm_sysfs.h b/include/drm/drm_sysfs.h
>> index 96a5d858404b..7695873a9456 100644
>> --- a/include/drm/drm_sysfs.h
>> +++ b/include/drm/drm_sysfs.h
>> @@ -3,13 +3,9 @@
>>   #define _DRM_SYSFS_H_
>>   struct drm_device;
>> -struct device;
>>   struct drm_connector;
>>   struct drm_property;
>> -int drm_class_device_register(struct device *dev);
>> -void drm_class_device_unregister(struct device *dev);
>> -
>>   void drm_sysfs_hotplug_event(struct drm_device *dev);
>>   void drm_sysfs_connector_hotplug_event(struct drm_connector 
>> *connector);
>>   void drm_sysfs_connector_property_event(struct drm_connector 
>> *connector,
>