linux-kernel - Re: [PATCH v4 2/9] spi: dt-bindings: add spi-{tx,rx}-lane-map properties

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Message-ID: <CAL_Jsq+y86RJ3PwN1DSbw1zUgL-f-R98u7s+zfrKr99V+za1Zw@mail.gmail.com>
Date: Thu, 8 Jan 2026 08:40:47 -0600
From: Rob Herring <robh@...nel.org>
To: Marcelo Schmitt <marcelo.schmitt1@...il.com>
Cc: David Lechner <dlechner@...libre.com>, Mark Brown <broonie@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Marcelo Schmitt <marcelo.schmitt@...log.com>, 
	Michael Hennerich <michael.hennerich@...log.com>, Nuno Sá <nuno.sa@...log.com>, 
	Jonathan Cameron <jic23@...nel.org>, Andy Shevchenko <andy@...nel.org>, 
	Sean Anderson <sean.anderson@...ux.dev>, linux-spi@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-iio@...r.kernel.org
Subject: Re: [PATCH v4 2/9] spi: dt-bindings: add spi-{tx,rx}-lane-map properties

On Thu, Jan 8, 2026 at 6:28 AM Marcelo Schmitt
<marcelo.schmitt1@...il.com> wrote:
>
> On 12/19, David Lechner wrote:
> > Add spi-tx-lane-map and spi-rx-lane-map properties to the SPI peripheral
> > device tree binding. These properties allow specifying the mapping of
> > peripheral data lanes to controller data lanes. This is needed e.g. when
> > some lanes are skipped on the controller side so that the controller
> > can correctly route data to/from the peripheral.
> >
> > Signed-off-by: David Lechner <dlechner@...libre.com>
> > ---
> >
> > v4 changes:
> > - This replaces the data-lanes property from the previous revision. Now
> >   there are separate properties for tx and rx lane maps. And instead of
> >   being the primary property for determining the number of lanes, this
> >   is only needed in special cases where the mapping is non-trivial.
> > ---
> >  .../devicetree/bindings/spi/spi-peripheral-props.yaml      | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
> > index 59ddead7da14..2f278f145f78 100644
> > --- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
> > +++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
> > @@ -75,6 +75,13 @@ properties:
> >        enum: [0, 1, 2, 4, 8]
> >      default: [1]
> >
> > +  spi-rx-lane-map:
> > +    description: Mapping of peripheral RX lanes to controller RX lanes.
> > +      Each index in the array represents a peripheral RX lane, and the value
> > +      at that index represents the corresponding controller RX lane.
> These are peripheral props so I guess RX is from peripheral perspective.
> In that case, those would be routed to controller TX lanes, no?

I'm pretty sure it's the input to the controller like the other rx
properties. Like rx-delay is for reads.

I guess "peripheral RX lanes to controller RX lanes" is a bit oddly worded.

Rob