Re: [PATCH 6/6] dt-bindings: usb: ci-hdrc-usb2: Add more phy tuning properties

[Rob Herring <robh@kernel.org>]

On Thu, Oct 13, 2022 at 12:14:12PM +0200, Sascha Hauer wrote:
> On Wed, Oct 12, 2022 at 11:08:06AM -0500, Rob Herring wrote:
> > On Tue, Oct 11, 2022 at 10:29:24AM +0200, Sascha Hauer wrote:
> > > Following the example of samsung,picophy-dc-vol-level-adjust more
> > > phy tuning properties are added for configuring the remaining bitfields
> > > in the USBNC_n_PHY_CFG1 register.
> > 
> > All these properties really doesn't scale. These properties should go 
> > in the phy node as they are properties or the phy. There's no rule that 
> > you can only read properties from the driver's device node.
> 
> I understand and agree.
> 
> On i.MX8M we currently use the usb-nop-xceiv. I guess it's not an option
> to just add these properties there, so we'll need a phy node with a new
> compatible like fsl,imx8mm-usbphy. The driver would basically just
> register a usb-nop-xceiv and the node would be a container for the new
> property. Does this sound sane?

I think it would be fine if you do:

compatible = "fsl,imx8mm-usbphy", "usb-nop-xceiv";

You'll have to rework the usb-nop-xceiv schema 'select' like we have to 
do for any compatible appearing in multiple schema files.

Or don't have the fallback and add "fsl,imx8mm-usbphy" to the 
phy-generic.c driver. But that should be marked for stable for at least 
some compatibility with old kernels.

For existing kernel binaries to work, you have to go with the former 
option.

Rob