Re: [PATCH net-next v2 2/2] net: dsa: mxl-gsw1xx: reset the switch through reset-gpios

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Medium] net: dsa: mxl-gsw1xx: gsw1xx_probe() uses reset API for
  exclusive reset-gpios
--

commit 911ba1a0c2756adf7ef65c7eabd51481e6dc7a52
Author: Joseph Telaak <joseph@telaak.dev>

net: dsa: mxl-gsw1xx: reset the switch through reset-gpios

This commit asserts and deasserts the switch reset line in gsw1xx_probe()
via the reset controller API before accessing switch registers.

> diff --git a/drivers/net/dsa/lantiq/mxl-gsw1xx.c b/drivers/net/dsa/lantiq/mxl-gsw1xx.c
> index a26f78e1a44ce..94a7eff5e0077 100644
> --- a/drivers/net/dsa/lantiq/mxl-gsw1xx.c
> +++ b/drivers/net/dsa/lantiq/mxl-gsw1xx.c

[ ... ]

> @@ -737,6 +739,29 @@ static int gsw1xx_probe(struct mdio_device *mdiodev)
>  	if (!priv->gswip.hw_info)
>  		return -EINVAL;
>  
> +	/* The MDIO core handles reset-gpios only for PHYs. Reset the switch
> +	 * here, so it does not run with whatever the bootloader configured.
> +	 */
> +	reset = devm_reset_control_get_optional_exclusive(dev, NULL);
> +	if (IS_ERR(reset))
> +		return dev_err_probe(dev, PTR_ERR(reset),
> +				     "failed to get reset control\n");

[Severity: Medium]
Should gsw1xx_probe() request reset-gpios directly with
devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH) and
gpiod_set_value_cansleep() instead of going through the reset controller
API?

The binding in Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
only defines reset-gpios (not resets) for standalone GSW1xx switches, while
NET_DSA_MXL_GSW1XX in drivers/net/dsa/lantiq/Kconfig does not select or
depend on RESET_GPIO or RESET_CONTROLLER.  When CONFIG_RESET_GPIO is
disabled (it defaults to n), __fwnode_reset_control_get() does not fall
back to reset-gpios and devm_reset_control_get_optional_exclusive()
silently returns NULL, skipping the hardware reset and leaving the switch
in the bootloader-configured state where ports fail with -ENODEV.

Using the reset-gpio wrapper for an exclusive GPIO reset also fails in
__reset_add_reset_gpio_device() when GPIO flags exceed GPIO_ACTIVE_LOW
(-EINVAL) or #gpio-cells is not 2 (-ENOENT), and allocates a persistent
auxiliary device and software node that are never freed on unbind.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261108-mxl-gsw1xx-reset-v2-0-46c1da093893@telaak.dev?part=2