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

[Thomas Zimmermann]

Hi

Am 25.02.25 um 10:07 schrieb Aditya Garg:
> > On 25 Feb 2025, at 2:34 PM, Aditya Garg <gargaditya08@xxxxxxxx> wrote:
> >
> > 
> >
> > > On 25 Feb 2025, at 1:27 PM, Thomas Zimmermann <tzimmermann@xxxxxxx> 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


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Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
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