Re: [PATCH] leds: lp5860: Return an error for an out-of-range 'reg' property

[Lee Jones <lee@kernel.org>]

On Fri, 12 Jun 2026, Mert Seftali wrote:

> When fwnode_property_read_u32() succeeds but the channel number exceeds
> LP5860_MAX_LED, ret is 0. The error path then passes 0 to dev_err_probe()
> and returns 0, so an out-of-range "reg" value is silently treated as
> success instead of being rejected.
> 
> Set ret to -EINVAL in that case so the invalid channel is reported and
> propagated as an error.
> 
> Fixes: 3daf2c4ef82b ("leds: Add support for TI LP5860 LED driver chip")
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <error27@gmail.com>
> Closes: https://lore.kernel.org/r/202605210624.3gcr3prk-lkp@intel.com/
> Signed-off-by: Mert Seftali <mertsftl@gmail.com>
> ---
>  drivers/leds/rgb/leds-lp5860-core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/leds/rgb/leds-lp5860-core.c b/drivers/leds/rgb/leds-lp5860-core.c
> index fd0e2f6e6e0f..9eeb01b3e56a 100644
> --- a/drivers/leds/rgb/leds-lp5860-core.c
> +++ b/drivers/leds/rgb/leds-lp5860-core.c
> @@ -115,6 +115,8 @@ static int lp5860_iterate_subleds(struct lp5860_led *led, struct led_init_data *
>  
>  		ret = fwnode_property_read_u32(led_node, "reg", &channel);
>  		if (ret < 0 || channel > LP5860_MAX_LED) {

Whilst we're hear, let's split this out.  If 'fwnode_property_read_u32()'
fails, 'channel' is not populated.  While short-circuit evaluation protects
us here, separating the error paths would allow us to use the preferred
'if (ret)' check instead of 'if (ret < 0)'.  It would also let us provide a
more accurate error message, as 'reg' is not missing when it is simply out of
range.

> +			if (ret >= 0)
> +				ret = -EINVAL;

Avoid this nested check entirely by assigning 'ret = -EINVAL' directly
within a separate block for the out-of-range check.  This would keep the
flow a bit cleaner and easier to follow.

>  			dev_err_probe(led->chip->dev, ret,
>  				      "%pfwP: 'reg' property is missing. Skipping.\n", led_node);
>  			fwnode_handle_put(led_node);
> -- 
> 2.54.0
> 

-- 
Lee Jones