Re: [PATCH v4 2/2] drm/tiny: add driver for Apple Touch Bars in x86 Macs

[Thomas Zimmermann <tzimmermann@suse.de>]

Hi

Am 25.02.25 um 10:07 schrieb Aditya Garg:
>
>> On 25 Feb 2025, at 2:34 PM, Aditya Garg <gargaditya08@live.com> wrote:
>>
>> 
>>
>>> On 25 Feb 2025, at 1:27 PM, Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>>
>>> Hi
>>>
>>> Am 24.02.25 um 17:58 schrieb Aditya Garg:
>>> [...]
>>>>> +config DRM_APPLETBDRM
>>>>> +    tristate "DRM support for Apple Touch Bars"
>>>>> +    depends on DRM && USB && MMU
>>>>> +    select DRM_GEM_SHMEM_HELPER
>>>>> +    select DRM_KMS_HELPER
>>>>> +    select HID_APPLETB_BL
>>>> Btw I have a doubt regarding this dependency. While hid-appletb-bl has made into the linux-next tree, it has still not been merged into Linus' tree, and neither the drm tree I assume. It potentially could cause issues?
>>> Yes. We cannot merge this driver until we have this symbol in our tree. But that will happen sooner or later.
>>>
>>> More problematic is that your driver selects HID_APPLETB_BL. From what I've seen, this symbol is user configurable, so the driver shouldn't select it. You need to use 'depends on' instead of 'select' here.
>> Looking at this again, maybe it should be selected. If you see the kernel config of TINYDRM_HX8357D, which is also in drm/tiny, it is selecting BACKLIGHT_CLASS_DEVICE.

This driver does it wrong.

> To make things more clear,
>
> 1. hid-appletb-bl is for the backlight of the touchbar. The DRM code remains separate.
> 2. hid-multitouch is to make the touchbar a touch screen. You can still use the driver without the touch functionality.

If your driver does not require this, it shouldn't select or depend on it.

Best regards
Thomas


-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)