Re: [PATCH v3 1/2] iio: vadc: Qualcomm SPMI PMIC voltage ADC driver

Ivan T. Ivanov
2014-10-16T13:58:56Z

Hi,

On Sat, 2014-10-04 at 12:51 +0100, Jonathan Cameron wrote:
> On 02/10/14 13:08, Ivan T. Ivanov wrote:
> > +iio maintainers
> >
> > On Thu, 2014-10-02 at 12:29 +0300, Ivan T. Ivanov wrote:
> > > Hi Stan,
> > > >
> > > On 09/24/2014 03:56 PM, Stanimir Varbanov wrote:
> > > >
> > > <snip>
> > > >
> > > > +static int vadc_get_dt_data(struct vadc_priv *vadc, struct
> > > > device_node *node)
> > > > +{
> > > > + struct iio_chan_spec *iio_chan = vadc->iio_chans;
> > > > + const struct vadc_channels *vadc_chan;
> > > > + struct vadc_channel_prop prop;
> > > > + struct device_node *child;
> > > > + int ret, index = 0;
> > > > +
> > > > + for_each_available_child_of_node(node, child) {
> > > > + ret = vadc_get_dt_channel_data(vadc->dev, &prop,
> > > > child);
> > > > + if (ret)
> > > > + return ret;
> > > > +
> > > > + vadc->chan_props[index] = prop;
> > > > +
> > > > + vadc_chan = &vadc_chans[prop.channel];
> > > > +
> > > > + iio_chan->channel = prop.channel;
> > > > + iio_chan->datasheet_name = vadc_chan->datasheet_name;
> > > > + iio_chan->info_mask_separate = vadc_chan->info_mask;
> > > > + iio_chan->type = vadc_chan->type;
> > > > + iio_chan->indexed = 1;
> > > > + iio_chan->scan_type.sign = 's';
> > > > + iio_chan->scan_type.realbits = 15;
> > > > + iio_chan->scan_type.storagebits = 16;
> > > > + iio_chan->address = index++;
> > > > +
> > > > + iio_chan++;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > >
> > > <snip>
> > > >
> > > > +static int vadc_probe(struct platform_device *pdev)
> > > > +{
> > > >
> > > <snip>
> > > >
> > > > +
> > > > + indio_dev->dev.parent = dev;
> > > > + indio_dev->dev.of_node = node;
> > > > + indio_dev->name = pdev->name;
> > > > + indio_dev->modes = INDIO_DIRECT_MODE;
> > > > + indio_dev->info = &vadc_info;
> > > > + indio_dev->channels = vadc->iio_chans;
> > > > + indio_dev->num_channels = vadc->nchannels;
> > > >
> > > This will not work as we thought. Registration will be fine and
> > > entries
> > > in sysfs are created as expected, but this is breaking
> > > numbering scheme
> > > for client drivers. For us the problem is that iio framework
> > > expect channels
> > > numbering to be linear and channel number should not be greater
> > > than
> > > channel count. For example even if die temperature channel is
> > > always 8, if
> > > I describe only 5 channels in DTS files (4 for reference points
> > > measurement)
> > > and 1 for die temperature, clients could not get OF reference to
> > > temperature
> > > channel using io-channels = <&pm8941_vadc 8>;
> > > >
> > > Jonathan, please, could you advise us.
> I'd like to let the solution you proposed sit on the list a little
> longer.
> It seems fairly sensible, but lets see what others suggest.

It is quiet :-) Just for the record the same aproach is used in
PWM, Reset, Gpio and PHY frameworks.

Patch in question: https://lkml.org/lkml/2014/10/2/199

Regards,
Ivan

>
> Jonathan