linux-kernel - Re: [PATCH v5 4/9] spi: add multi_lane_mode field to struct spi

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Message-ID: <20260114090604.031ed4f0@jic23-huawei>
Date: Wed, 14 Jan 2026 09:06:04 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: David Lechner <dlechner@...libre.com>
Cc: Mark Brown <broonie@...nel.org>, Rob Herring <robh@...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>, 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 v5 4/9] spi: add multi_lane_mode field to struct
 spi_transfer

On Mon, 12 Jan 2026 11:45:22 -0600
David Lechner <dlechner@...libre.com> wrote:

> Add a new multi_lane_mode field to struct spi_transfer to allow
> peripherals that support multiple SPI lanes to be used with a single
> SPI controller.
> 
> This requires both the peripheral and the controller to have multiple
> serializers connected to separate data lanes. It could also be used with
> a single controller and multiple peripherals that are functioning as a
> single logical device (similar to parallel memories).
> 
> Acked-by: Nuno Sá <nuno.sa@...log.com>
> Acked-by: Marcelo Schmitt <marcelo.schmitt@...log.com>
> Signed-off-by: David Lechner <dlechner@...libre.com>
Fwiw looks fine to me (and so a tag mostly so I don't read it again in v6 
if that happens!)
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>

> ---
> 
> v4 changes:
> * Shortened commit message (useful info will be in docs instead).
> * Added whitespace to create clear grouping of macros and the field.
> 
> v3 changes:
> * Renamed "buses" to "lanes" to reflect devicetree property name change.
> ---
>  include/linux/spi/spi.h | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 7aff60ab257e..eba7ae8466ac 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -981,6 +981,8 @@ struct spi_res {
>   *      (SPI_NBITS_SINGLE) is used.
>   * @rx_nbits: number of bits used for reading. If 0 the default
>   *      (SPI_NBITS_SINGLE) is used.
> + * @multi_lane_mode: How to serialize data on multiple lanes. One of the
> + *      SPI_MULTI_LANE_MODE_* values.
>   * @len: size of rx and tx buffers (in bytes)
>   * @speed_hz: Select a speed other than the device default for this
>   *      transfer. If 0 the default (from @spi_device) is used.
> @@ -1117,6 +1119,12 @@ struct spi_transfer {
>  	unsigned	cs_change:1;
>  	unsigned	tx_nbits:4;
>  	unsigned	rx_nbits:4;
> +
> +#define SPI_MULTI_LANE_MODE_SINGLE	0 /* only use single lane */
> +#define SPI_MULTI_LANE_MODE_STRIPE	1 /* one data word per lane */
> +#define SPI_MULTI_LANE_MODE_MIRROR	2 /* same word sent on all lanes */
> +	unsigned	multi_lane_mode: 2;
> +
>  	unsigned	timestamped:1;
>  	bool		dtr_mode;
>  #define	SPI_NBITS_SINGLE	0x01 /* 1-bit transfer */
>