On Wed, 28 Feb 2024 17:11:59 +0900 Dominique Martinet <dominique.martinet@xxxxxxxxxxxxxxxxx> wrote: > Krzysztof Kozlowski wrote on Wed, Feb 28, 2024 at 08:42:46AM +0100: > > >> Sorry, that's why you have labels and compatibles. > > > > > Setting up a fixed alias seems to be precisely what aliases are about > > > (e.g. setting rtc0 will make a specific node become /dev/rtc0, same with > > > ethernet0, gpio, i2c, mmc, serial...), I'm not sure I agree a new label > > > would be more appropriate here, but perhaps I'm missing some context? > > > > Maybe I don't get your point, but your email said "sysfs", so why do you > > refer to /dev? > > I wrote /dev/rtc0, but it also sets the name in /sys, right? > For example /sys/class/rtc/rtc0 > > As far as I'm aware iio also creates character devices in /dev with the > same name (/dev/iio/iio:deviceX), but our application doesn't use these > at all and has to? look in /sys directly, so normal udev SYMLINK+= > unfortunately isn't applicable or I wouldn't be bothering with all > this.. A given IIO device driver may create multiple sysfs directories (registers device + one or more triggers), so I'm not sure how this would work. > > > > I'm not sure I understand this comment -- would you rather this doesn't > > > use aliases but instead add a new label (e.g. `iio,index = <10>` or > > > whatever) to the iio node itself? > > > > No, the devices already have label property. > > Thank you for pointing me at the 'label' property, looking at other > subsystems e.g. leds I see paths in sysfs that use labels as I'd like it > to work for iio (/sys/class/leds/<label> and > /sys/devices/platform/<parent>/leds/<label>) > > Unfortunately for iio it looks like labels isn't ignored, but instead > create a file in the sysfs directory of the device, e.g. I now have > /sys/bus/iio/devices/iio:device1/label which contains the label string, > so I'm not sure that can be changed easily as that'd be a change of API > for existing users for labels in iio devices? Yes, don't touch that ABI. IIO software assumes naming of iio\:deviceX etc. > > (I checked briefly and didn't find any, but there seems to be an awful > lot of code in the iio drivers tree about labels so I'm not really > comfortable changing that without some more background on iio first... > Jonathan perhaps has an opinion on this?) There are labels for channels as well as devices, but the short description you have above is it. I don't see why that isn't sufficient for your use case though? What does a directory name matter when you can write a few lines of code to retrieve the IIO device that you want. If this was day 0 maybe we could support renaming devices like this but we have a long history of those names not being stable and label + parentage of the IIO devices being used to establish stable identification. Anything beyond a trivial single use script is going to need to deal with not having stable names (old kernel, dt without alias etc) so this doesn't help in general. Jonathan > > > Thanks,
