Re: [PATCH v1 1/1] hwmon: (isl28022) Don't check for specific errors when parsing properties

[Guenter Roeck]

On 2/19/26 06:30, Andy Shevchenko wrote:
> On Thu, Feb 19, 2026 at 03:21:29PM +0100, Geert Uytterhoeven wrote:
> > On Thu, 19 Feb 2026 at 15:06, Andy Shevchenko
> > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > > Instead of checking for the specific error codes (that can be considered
> > > a layering violation to some extent) check for the property existence first
> > > and then either parse it, or apply a default value.
>
> > IIRC, we have removed superfluous presence checks all over the tree
> > during the past few years? E.g. of_property_read_*() is documented to
> > return -EINVAL if a property does not exist.
>
> Even though, it's still fragile. When we have a check for explicit device
> presence, we wouldn't care of the error code we get in case of unsuccessful
> parsing.
>
> > So this patch looks like a step back to me...
>
> Obviously I have a disagreement here, this is step forward to weaken
> the dependency on the certain error code in the cases when we can avoid
> that. Motivation is mentioned in the commit message.
>
> Also note, -EINVAL can sneak in tons of mysterious ways as it's one of
> the most overloaded error code in the kernel, its semantic is basically
> equals to "an error happened".
>
> Having the code above, we make it robust against some subtle nuances which
> may not be discovered in time.

Is that documented somewhere ? I have been asking people to use the current
approach to reduce code size. device_property_present() isn't even mentioned
as API in Documentation/. If "do not rely on error codes from device property
API functions to determine if a default should be applied" or similar is a new
rule or guidance, it should be clearly documented somewhere.

Thanks,
Guenter