On 19/07/16 07:55, Quentin Schulz wrote: > On 18/07/2016 14:24, Jonathan Cameron wrote: >> On 15/07/16 10:59, Quentin Schulz wrote: >>> Currently, iio_hwmon only exposes values of the IIO channels it can read >>> but no label by channel is exposed. >>> >>> This adds exposition of sysfs files containing label for IIO channels it >>> can read based on extended_name field of the iio_chan_spec of the channel. >>> If the extended_name field is empty, the sysfs file is not created by >>> iio_hwmon. >> Hmm. This is not the intent of extended name at all. That exists to add >> a small amount of information to an constructed IIO channel name. >> Typically it's used to indicate physically wired stuff like: >> >> in_voltage0_vdd_raw for cases where that channel of the ADC is hard wired >> to the vdd. In this particular case the use might actually work as the >> vdd makes it clear it's a voltage - in general that's not the case. >> >> Use of extended_name at all in IIO is only done after extensive review. >> It adds nasty custom ABI to a device, so the gain has to be considerable >> to use it. >> >> When I read your original suggestion of adding labels, I was expecting the >> use of datasheet_name. That has the advantage of being well defined by >> the datasheet (if not it should not be provided) + not being used in >> the construction of the IIO channel related attributes. However, that >> may still not correspond well to the expected labelling in hwmon. > > Good to know for extend_name use cases. While doing further testing, I > noticed the extend_name is also appended to the sysfs filename.. which > is definitely not what we want. > > I've checked for datasheet_name and it is only used to be compared to > adc_channel_label from iio_map structure. Same for adc_channel_label > (which has to be the same as datasheet_name of the iio_chan_spec it is > linked to). So I could use this instead of extend_name to put a label on > a channel. > However, I thought of it to be more a way to identify the hardware in > the datasheet more than giving users a hint on what it is. That's what > "git grep adc_channel_label" told me. It's definitely better to use > datasheet_name over extend_name for channel labeling but I don't know if > it's really the good variable to use for labeling? In my understanding > of datasheet_name, in my case it would be more "temp_gpadc" than "SoC > temperature", that's what I mean. If we are going to do this I think we need a new field in iio_chan_spec for it. The problem as ever is going to be that we'll end up with 'fuzzy' ABI which we can't change - even if we end up with spelling mistakes sneaking through review - or entirely incorrect labels. > >> Thinking more on this, the label is going to often be a function of how >> the board is wired up... Perhaps it should be a characteristic of the >> channel_map (hence from DT or similar) rather than part of the IIO driver >> itself? > > Hmm.. I would not put a property in the DT only for labeling. It's an odd one because in many cases the map (which is effectively representing a wire) is the only relevant place to have such a label. Can see what you mean about not putting things in DT which are basically 'help'! > > [...] > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
