Re: [PATCH v2] leds: class: Use firmware nodes for device lookup

[Tommaso Merciai]

Hi Alban,
Thanks for your comments.

On Tue, Jun 09, 2026 at 06:54:29PM +0200, Alban Bedel wrote:
> On Tue, 9 Jun 2026 16:46:36 +0200
> Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx> wrote:
> 
> > Hi Lee,
> > Thanks for your patch.
> > 
> > On Wed, May 20, 2026 at 04:22:25PM +0100, Lee Jones wrote:
> > [...]
> > > What happens if fwnode_property_match_string() returns an error?  
> > 
> > Agree.
> > 
> > I think we need to check index:
> > 		if (index < 0)
> > 			return ERR_PTR(-ENOENT);
> 
> I don't think that's the right solution. The documentation of
> fwnode_property_get_reference_args() says that it return -ENOENT
> when the index is out range. So it looks like the OF implementation
> has a bug.
> 
> Looking at of_fwnode_get_reference_args() it directly pass the return
> value of __of_parse_phandle_with_args(), which return -EINVAL when the
> index is out of range. We should rather fix the OF implementation of
> fwnode_property_get_reference_args() to respect the documented
> interface.

Maybe into of_fwnode_get_reference_args() first thing to do is to check
index with:

	if (index > INT_MAX)
		return -ENOENT;

fwnode_led_get()
    fwnode_property_match_string() -> "led-names" not exist -> index = -EINVAL (-22, int)
    fwnode_find_reference(fwnode, "leds", index)
        /* int(-22) -> unsigned int( index > INT_MAX), fwnode_find_reference takes unsigned int */
        fwnode_property_get_reference_args(fwnode, name, NULL, 0, index, &args)
            of_fwnode_get_reference_args()
                /* index is already unsigned int( index > INT_MAX) */
                of_parse_phandle_with_fixed_args(, index,)
                    /* unsigned int(index > INT_MAX) -> int(-22), takes int */
                    __of_parse_phandle_with_args()
                        if (index < 0)
                            return -EINVAL;


Not sure. What do you think?

Thanks, Tommaso

> 
> Alban
>