Hi, 

On Sat, 2014-10-04 at 12:51 +0100, Jonathan Cameron wrote:

On 02/10/14 13:08, Ivan T. Ivanov wrote:

quoted

 +iio maintainers

 On Thu, 2014-10-02 at 12:29 +0300, Ivan T. Ivanov wrote:

quoted

 Hi Stan,

quoted

 On 09/24/2014 03:56 PM, Stanimir Varbanov wrote:

quoted

 <snip>

quoted

 +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>

quoted

 +static int vadc_probe(struct platform_device *pdev)
 +{

 <snip>

quoted

 +
 +      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>;

quoted

 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