Re: [PATCH v8 5/8] iio: dac: ad5686: implement new sync() op for the spi bus

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Use of the C++ / C23 `auto` keyword for type inference causes a compilation error in standard Linux kernel C.
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--- Patch [5]: [PATCH v8 5/8] iio: dac: ad5686: implement new sync() op for the spi bus ---
commit 6524307465bd775ca4dd7375ae2bb7b554ff6dde
Author: Rodrigo Alencar <rodrigo.alencar@analog.com>

iio: dac: ad5686: implement new sync() op for the spi bus

This commit introduces a new sync() operation for the SPI bus to handle
multiple channel DAC writes more efficiently. It stores SPI transfers in
a message and flushes them to the platform driver during the sync operation.

> diff --git a/drivers/iio/dac/ad5686-spi.c b/drivers/iio/dac/ad5686-spi.c
> index d3b64b4361d51..2cb836038821f 100644
> --- a/drivers/iio/dac/ad5686-spi.c
> +++ b/drivers/iio/dac/ad5686-spi.c
[ ... ]
> @@ -13,59 +13,101 @@
>  static int ad5686_spi_write(struct ad5686_state *st,
>  			    u8 cmd, u8 addr, u16 val)
>  {
> -	struct spi_device *spi = to_spi_device(st->dev);
> -	u8 tx_len, *buf;
> -
> +	struct ad5686_spi_data *bus_data = st->bus_data;
> +	struct spi_transfer *xfer;
> +
> +	if (bus_data->size >= bus_data->capacity)
> +		return -E2BIG;
> +
> +	/*
> +	 * This function stores spi transfers to a spi message to be sent over
> +	 * the bus when sync() op is called. If there are already transfers in
> +	 * the spi message, set the cs_change flag on the last transfer to
> +	 * ensure that the chip select is deasserted between transfers. If this
> +	 * is the first transfer, initialize the spi message. Later on, the
> +	 * current transfer is added to the message with spi_message_add_tail().
> +	 */
> +	if (bus_data->size)
> +		bus_data->xfers[bus_data->size - 1].cs_change = 1;
> +	else
> +		spi_message_init(&bus_data->msg);
> +
> +	xfer = &bus_data->xfers[bus_data->size];
> +	auto buf = &st->data[bus_data->size];

[Severity: Low]
Will this cause a compilation error? Standard GNU C11 used in the Linux kernel
does not support the C++ or C23 auto keyword for type deduction.

>  	switch (st->chip_info->regmap_type) {
>  	case AD5310_REGMAP:

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716-ad5686-new-features-v8-0-ebb0051af5e5@analog.com?part=5