Re: [PATCH v2 2/2] mfd: cros_ec: Read EC features during probe to catch transfer error

[Lee Jones]

On Mon, 08 Jun 2026, Andrei Kuchynski wrote:

> cros_ec_check_features() does not return an error if the underlying
> EC_CMD_GET_FEATURES command fails. Consequently, when the Fingerprint
> device fails to respond, the probe function ignores the failure and falls
> back to installing it as 'cros_ec' device instead of 'cros_fp'.
> This leads to a sysfs duplicate filename collision later when the real
> 'cros_ec' device attempts to register:
> 
>   cros-ec-spi spi5.0: EC failed to respond in time
>   cros-ec-dev.19.auto: cannot get EC features: -110
>   sysfs : cannot create duplicate filename '/class/chromeos/cros_ec'
>         : sysfs_do_create_link_sd+0x94/0xdc
>         : ec_device_probe+0x150/0x4f0
> 
> Fix this by explicitly calling the newly introduced cros_ec_read_features()
> function. If the transfer fails, abort the broken device initialization.
> Move the initialization of class_dev before this call to prevent a missing
> release() callback warning on the error path.
> 
> Signed-off-by: Andrei Kuchynski <akuchynski@xxxxxxxxxxxx>
> ---
>  drivers/mfd/cros_ec_dev.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> index 39430dd44e30c..a8c6300248d59 100644
> --- a/drivers/mfd/cros_ec_dev.c
> +++ b/drivers/mfd/cros_ec_dev.c
> @@ -203,6 +203,17 @@ static int ec_device_probe(struct platform_device *pdev)
>  	ec->features.flags[1] = -1U; /* Not cached yet */
>  	device_initialize(&ec->class_dev);
>  
> +	/*
> +	 * Add the class device
> +	 */
> +	ec->class_dev.class = &cros_class;
> +	ec->class_dev.parent = dev;
> +	ec->class_dev.release = cros_ec_class_release;
> +
> +	retval = cros_ec_read_features(ec);

This depends on the other patch.

Once it's been Reviewed / Acked, I'd be happy to take both and submit an IB.

> +	if (retval < 0)
> +		goto failed;
> +
>  	for (i = 0; i < ARRAY_SIZE(cros_mcu_devices); i++) {
>  		/*
>  		 * Check whether this is actually a dedicated MCU rather
> @@ -220,13 +231,6 @@ static int ec_device_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> -	/*
> -	 * Add the class device
> -	 */
> -	ec->class_dev.class = &cros_class;
> -	ec->class_dev.parent = dev;
> -	ec->class_dev.release = cros_ec_class_release;
> -
>  	retval = dev_set_name(&ec->class_dev, "%s", ec_platform->ec_name);
>  	if (retval) {
>  		dev_err(dev, "dev_set_name failed => %d\n", retval);
> -- 
> 2.54.0.1032.g2f8565e1d1-goog
> 

-- 
Lee Jones