Re: [PATCH 2/3] dt-bindings: spi: Add DT schema for Tegra SPIDEV controller

[Jon Hunter]

On 31/03/2025 13:44, Mark Brown wrote:
> On Mon, Mar 31, 2025 at 01:34:21PM +0100, Jon Hunter wrote:
> > On 27/03/2025 15:33, Mark Brown wrote:
> > > On Wed, Mar 26, 2025 at 12:16:53PM +0000, Jon Hunter wrote:
>
> > > > That's definitely what we do today, modify the kernel directly to achieve
> > > > what we need. I am trying to avoid carrying too many out of tree patches for
> > > > stuff like this and have something in the kernel that works by default. This
> > > > is even more important for 3rd party Linux distros that will not accept
> > > > non-upstream code.
>
> > > Overlays should work well for that case too!
>
> > If you mean device-tree overlays, I don't see how that will work today.
> > Unless we are to use one of the existing compatible strings, but that feels
> > wrong because we are not using any of those devices and like I mentioned,
> > just using 'spidev' alone in device-tree does not work with the latest
> > kernels.
>
> Why would you need to use a compatible string for anything?  I'd expect
> the overlay to add the entire new device, compatible and all.


We need a compatible string for the SPI device in device-tree. Sorry, 
but I am not sure how we can add a SPI device without one.

Can you confirm what you mean by 'overlay'? To me an overlay, is purely 
a device-tree overlay and even if we have a device-tree overlay, we are 
still missing the kernel driver part that matches the compatible string.

I could be completely missing your point here, but it is not obvious to 
me what you are suggesting?

Jon

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