RE: [PATCH v2 3/3] i2c: smbus: Use device_*() functions instead of of_*()

Akhil R
2022-01-20T10:29:14Z

> ...
>
> > > This change reveals potential issue:
> > >
> > > > - irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert");
> > > > + irq = device_irq_get_byname(adapter->dev.parent,
> "smbus_alert");
> > >
> > > > if (irq <= 0)
> > >
> > > I guess this '= 0' part should be fixed first.
> >
> > '0' is a failure as per the documentation of of_irq_get_byname() as well as
> > of_irq_get(). The case is different for acpi_irq_get(), but it is handled in
> > fwnode_irq_get(). If I understood it right, a return value of '0' should be
> > considered a failure here.
>
> Depends. I have no idea what the original code does here. But
> returning an error or 0 from this function seems confusing to me.
>
The description in of_irq_get*() says -
/* Return: Linux IRQ number on success, or 0 on the IRQ mapping failure, or
* -EPROBE_DEFER if the IRQ domain is not yet created, or error code in case
* of any other failure.
*/
As I see from the code of fwnode_irq_get(), which is used in this case, returns
either the return value of of_irq_get() or error code from acpi_irq_get() when
it fails, or res.start if it didn't fail. I guess, any of these would not be 0 unless
there is an error.

Thanks,
Akhil