Re: [PATCH v11 03/19] spi: parse spi-max-post-config-frequency-hz into post_config_max_speed_hz

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] spi: unclamped post_config_max_speed_hz in __spi_setup()
--

commit 3a575dbc26c781e2f3bb4d2e533de6da92715c51
Author: Santhosh Kumar K <s-k6@ti.com>

spi: parse spi-max-post-config-frequency-hz into post_config_max_speed_hz

This commit adds post_config_max_speed_hz to struct spi_device and parses
it from the spi-max-post-config-frequency-hz device tree property in
of_spi_parse_dt(). This allows SPI devices to specify a higher target
clock frequency to be used after controller-side configuration such as PHY
tuning.

> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index c29ffac59c8f0..3f6add21154ed 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -2825,6 +2825,8 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
>  	/* Device speed */
>  	if (!of_property_read_u32(nc, "spi-max-frequency", &value))
>  		spi->max_speed_hz = value;
> +	if (!of_property_read_u32(nc, "spi-max-post-config-frequency-hz", &value))
> +		spi->post_config_max_speed_hz = value;

[Severity: Medium]
As reported by Sashiko on v4 [1], when a device tree node specifies a
spi-max-post-config-frequency-hz value that exceeds the parent controller's
spi->controller->max_speed_hz limit, can spi->post_config_max_speed_hz
remain uncapped?

During device registration, of_register_spi_device() calls of_spi_parse_dt()
and then spi_add_device() -> __spi_add_device() -> __spi_setup(). In
__spi_setup(), spi->max_speed_hz is clamped to the controller's maximum
speed, but spi->post_config_max_speed_hz is not:

drivers/spi/spi.c:__spi_setup() {
    ...
	if (spi->controller->max_speed_hz &&
	    (!spi->max_speed_hz ||
	     spi->max_speed_hz > spi->controller->max_speed_hz))
		spi->max_speed_hz = spi->controller->max_speed_hz;
    ...
}

Should __spi_setup() also clamp spi->post_config_max_speed_hz to
spi->controller->max_speed_hz when both are non-zero, so that
post-configuration SPI-MEM operations and PHY tuning do not request a
frequency above the controller's hardware limit?

[1] https://lore.kernel.org/r/20260618075445.389E11F000E9@smtp.kernel.org

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261105105832.2134313-1-s-k6@ti.com?part=3

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