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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Mon, 16 Aug 2021 11:07:00 +0300
Message-ID: <CAHp75VeNJ1fuo5dVfhk+w9H+0angfJEDPUVHUKk=Kgc=zNP8Fw@mail.gmail.com>
Subject: Re: [PATCH v5 3/5] iio: adc: ad7949: add support for internal vref
To:     Liam Beguin <liambeguin@gmail.com>
Cc:     Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Michael Hennerich <Michael.Hennerich@analog.com>,
        Charles-Antoine Couret <charles-antoine.couret@essensium.com>,
        =?UTF-8?B?TnVubyBTw6E=?= <Nuno.Sa@analog.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-iio <linux-iio@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>
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On Fri, Aug 13, 2021 at 11:51 PM Liam Beguin <liambeguin@gmail.com> wrote:
> On Mon Aug 9, 2021 at 3:42 PM EDT, Jonathan Cameron wrote:

...

> > > > > +       /* Read channel specific information form the devicetree */

from

> > > > > +       device_for_each_child_node(dev, child) {
> > > > > +               ret = fwnode_property_read_u32(child, "reg", &i);
> > > > > +               if (ret) {
> > > > > +                       dev_err(dev, "missing reg property in %pfw\n", child);
> > > > > +                       fwnode_handle_put(child);
> > > > > +                       return ret;
> > > > > +               }
> > > > > +
> > > > > +               ad7949_chan = &ad7949_adc->channels[i];
> > > > > +
> > > > > +               ret = fwnode_property_read_u32(child, "adi,internal-ref-microvolt", &tmp);
> > > > > +               if (ret < 0 && ret != -EINVAL) {
> > > > > +                       dev_err(dev, "invalid internal reference in %pfw\n", child);
> > > > > +                       fwnode_handle_put(child);
> > > > > +                       return ret;
> > > > > +               }

> After getting access to another setup to run more tests, I noticed
> that setting the reference per channel isn't really feasible.

Is it a hardware limitation?

-- 
With Best Regards,
Andy Shevchenko