Re: [PATCH v4 1/2] dt-bindings: i3c: Add adi-i3c-master

Jorge Marques
2025-07-02T12:02:13Z

On Fri, Jun 27, 2025 at 06:02:26PM +0200, Jorge Marques wrote:
> On Fri, Jun 27, 2025 at 04:49:19PM +0200, Krzysztof Kozlowski wrote:
> > On 27/06/2025 16:38, Jorge Marques wrote:
> > > On Fri, Jun 27, 2025 at 08:56:55AM +0200, Krzysztof Kozlowski wrote:
> > >> On Thu, Jun 26, 2025 at 12:07:36PM +0200, Jorge Marques wrote:
> > >>> Add bindings doc for ADI I3C Controller IP core, a FPGA synthesizable IP
> > >>> core that implements the MIPI I3C Basic controller specification.
> > >>
> > >> How did you resolve my last comment? I don't see any explanation -
> > >> neither here nor in the binding description. Binding description is
> > >> actually better place, I think now.
> > >>
> > >> Best regards,
> > >> Krzysztof
> > >>
> > >
> > > Hi Krzysztof,
> > >
> > > I forgot to condense out discussion on v4.
> > > What about this binding description:
> > >
> > > description: |
> > > FPGA-based I3C controller designed to interface with I3C and I2C
> > > peripherals, implementing a subset of the I3C-basic specification.
> > > The IP core is tested on arm, microblaze, and arm64 architectures.
> > > It takes one or two clocks, axi and i3c. If only axi is provided,
> > > then there is no clock signal to the i3c input clock pin and axi
> >
> > This is obvious from the schema, drop.
> Ack.
>
> >
> > > clock drives the whole IP. The compatible is suffixed by 1.00.a
> > > foreseeing future controllers by Analog Devices Inc. and breaking
> > > changes.
> >
> > I don't understand that. How are you breaking any changes? And how
> > 1.00.a predicts future? I don't think this reflects previous discussion.
> > Why you were asked to go with v1.00.a?
> The -1.00.a suffix came from this discussion:
>
> https://lore.kernel.org/linux-i3c/ildi2pup2zkyv4stuknkrjysex3yzsbrrsrwbgcc4xgvdhwrdd@7qh4y6mutgy2/
>
> Other adi bindings use this suffix. I personally wouldn't add any suffix
> unless told otherwise, as I expressed on the thread. Should I drop it?
> or suffix it with something else?
> >
> > Best regards,
> > Krzysztof
>
> Best regards,
> Jorge

Hi Krzysztof and Conor,

I went after the reason of the historically -1.00.a suffix and
discovered that they came into existence due to AMD Xilinx auto
generation devicetree tool SDTGen
https://github.com/Xilinx/system-device-tree-xlnx
that would automatically suffix with the IP version, defaulting to 1.00.a,
and for a seamless experience, the were copied over to the dt-bindings.

The adi,axi-pwmgen dt-binding went more creative and suffixed with
-2.00.a, while never enforcing Vivado to yield the devicetree with such
value (Major version is asserted in the driver through reg access, the
current core version is v2.1.1)

Testing on my side (AMD Xilinx Vivado 2024.2), it seems Vivado now
defaults to 1.0, so the previous bindings from the other IPs are not
accurate anymore, either, (axi-pwmgen auto gens
`compatible = "xlnx,axi-pwm-gen-1.0";` (`xlnx` instead of `adi`, also)).

For fun, the current Vivado version thinks the devicetree node for the
i3c master should be as follows:

i3c_host_interface: i3c_controller_host_interface@44a00000 {
compatible = "xlnx,i3c-controller-host-interface-1.0";
reg = <0x44a00000 0x10000>;
clocks = <&clkc 15>;
clock-names = "s_axi_aclk";
};

Let me know if we can drop the suffix, or replace with something else.
The current register defined core version is v0.1.0.

Best regards,
Jorge