Subject: Re: [PATCH 0/8] can: flexcan: add CAN FD support for NXP Flexcan

From: Shawn Guo <[email-masked]>
Date: Tue, 18 Feb 2020 17:33:51 +0800

On Mon, Feb 17, 2020 at 09:48:36AM +0100, Michael Walle wrote:
> > My opinion is that all compatibles should be defined explicitly in
> > bindings doc.  In above example, the possible values of <processor>
> > should be given.  This must be done anyway, as we are moving to
> > json-schema bindings.
> 
> But if they are listed in the document, they also have to be in the
> of_device_id table, correct?

I do not think so.  Documenting compatibles used in DTS now doesn't
necessarily mean we need to use it in kernel driver right away.
Bindings doc is a specification for device tree, not kernel.  With the
compatible in DTS and bindings, kernel can start using it at any time
when there is a need, like dealing with SoC quirks or bugs found later.

Shawn

> Which somehow contradicts the talk Pankaj
> mentioned [1,2]. Eg.
> 
>   compatible = "fsl,ls1028ar1-flexcan","fsl,lx2160ar1-flexcan";
> 
> Doesn't make any sense, because the "fsl,ls1028ar1-flexcan" is alreay
> in the driver and the fallback "fsl,lx2160ar1-flexcan" isn't needed.
> 
> OTOH the talk is already 2 to 3 years old and things might have changed
> since then.
> 
> -michael
> 
> [1] https://elinux.org/images/0/0e/OSELAS.Presentation-ELCE2017-DT.pdf
> [2] https://www.youtube.com/watch?v=6iguKSJJfxo