On Mon, 16 Aug 2021 16:12:58 +0300
Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote:
> On Mon, Aug 16, 2021 at 4:07 PM Liam Beguin <liambeguin@xxxxxxxxx> wrote:
> > On Mon Aug 16, 2021 at 8:48 AM EDT, Andy Shevchenko wrote:
> > > On Mon, Aug 16, 2021 at 3:39 PM Liam Beguin <liambeguin@xxxxxxxxx>
> > > wrote:
> > > > On Mon Aug 16, 2021 at 4:04 AM EDT, Andy Shevchenko wrote:
> > > > > On Mon, Aug 16, 2021 at 12:35 AM Liam Beguin <liambeguin@xxxxxxxxx>
> > > > > wrote:
>
> ...
>
> > > > > > + tmp = 4096000;
> > > > > > + ret = device_property_read_u32(dev, "adi,internal-ref-microvolt", &tmp);
> > > > >
> > > > > > + if (ret < 0 && ret != -EINVAL) {
> > > >
> > > > Hi Andy,
> > > >
> > > > >
> > > > > What does this check (second part) is supposed to mean?
> > > > > The first part will make it mandatory, is it the goal?
> > > > >
> > > >
> > > > device_property_read_u32() will return -EINVAL if the property isn't
> > > > found in the devicetree.
> > > >
> > > > This checks for errors when the property is defined while keeping it
> > > > optional.
> > >
> > > Don't assign and don't check the error code of the API. As simply as
> > > that.
> >
> > I'm not against getting rid of it, but I was asked to check for these
> > errors in earlier revisions of the patch.
>
> Okay, I leave it to you, guys, to decide, just note that the usual
> pattern for optional stuff
> a) either check for (!ret);
> b) or ignore the returned value completely.
Hmm. My thinking (I suspect I asked for it to be checked, but can't remember :)
was that I'd really like to know if a device tree contains a property but that
property is invalid for some reason. The docs give a bunch of reasons beyond
the property not existing (which is unhelpfully described as just 'invalid parameters').
I guess that's a bit far fetched. Let's drop the check as Andy suggests.
Dropped that check and applied to the togreg branch of iio.git, initially pushed out
as testing for 0-day to poke at it. + we are about to enter merge window so I don't
want linux-next to pick it up just yet!
Jonathan
>
> > > > > > + dev_err(dev, "invalid value for adi,internal-ref-microvolt\n");
> > > > > > + return ret;
> > > > > > + }
>
>
