Re: [PATCH v2 1/2] devicetree: i2c-hid: Add Wacom digitizer + regulator support

From: Jiri Kosina
Date: Fri Dec 09 2016 - 09:36:45 EST

On Thu, 8 Dec 2016, Rob Herring wrote:

> > And if tomorrow there is Elan device that is drop-in compatible (same
> > connector, etc) with Wacom i2c-hid, will you ask for Elan-specific
> > binding? Atmel? Weida? They all need to be powered up ultimately.
> Yes, I will.

What advantage does that bring?

> That in no way means the OS driver has to know about each and every one.
> If they can all claim compatibility with Wacom (including power
> control), then they can have a Wacom compatible string too. Or you can
> just never tell me that there's a different manufacturer and I won't
> care as long you don't need different control. But soon as a device
> needs another power rail, GPIO or different timing, then you'd better
> have a new compatible string.

Again, I simply don't understand what advantage does the aproach you are
trying to use bring.

HID over I2C is a generic protocol. Sure, we need to have quirks for
device-specific bugs, and in such cases enumerate particular devices. But
we don't need DT for that at all.

Jiri Kosina