Re: [PATCH v2 1/3] mips: dts: ralink: mt7621: associate uart1_pins with serial0

[Justin Swartz]

Hi Angelo

On 2024-03-08 10:41, AngeloGioacchino Del Regno wrote:
> Il 07/03/24 20:04, Justin Swartz ha scritto:
> > Add missing pinctrl-name and pinctrl-0 properties to declare
> > that the uart1_pins group is associated with serial0.
> >
> > Signed-off-by: Justin Swartz <justin.swartz@xxxxxxxxxxxxxxxx>
> > ---
> >   arch/mips/boot/dts/ralink/mt7621.dtsi | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/arch/mips/boot/dts/ralink/mt7621.dtsi 
> > b/arch/mips/boot/dts/ralink/mt7621.dtsi
> > index 35a10258f..dca415fdd 100644
> > --- a/arch/mips/boot/dts/ralink/mt7621.dtsi
> > +++ b/arch/mips/boot/dts/ralink/mt7621.dtsi
> > @@ -123,6 +123,9 @@ serial0: serial@c00 {
> >   			reg-shift = <2>;
> >   			reg-io-width = <4>;
> >   			no-loopback-test;
> > +
> > +			pinctrl-names = "default";
> > +			pinctrl-0 = <&uart1_pins>;
> >   		};
> >     		spi0: spi@b00 {
>
> The pins are muxed and can be either UART, or some other function that
> is supported by the mux: this means that the pinctrl-xxx properties 
> shall
> *not* go into the SoC dtsi file, but in board dts files instead.
>
> Said differently: the usage of the UART pins is board-specific, not 
> SoC-wide.

Thanks for the explanation. I agree that the pinctrl properties
would make more sense in a serial node extension in a board's dts,
but my reason for including them in the SoC's dtsi is due to the
precedent set with these existing nodes:

  i2c
  spi0
  mmc
  ethernet
  pcie

There is also a default function declared for each of the pin
groups defined under the pinctrl node. These functions co-incide
with what is intended for each of those device nodes to function
correctly, rather than in the alternative GPIO-mode.

So I thought that sticking with that existing pattern would get
the least resistance from the community.

I can imagine how moving the pinctrl node to the board dts, and
then moving all of the pinctrl properties associated with device
nodes to their board dts references could be a better separation
logically.

What do you recommend?

Regards
Justin