Hi,
When we were using kernel 3.2 and with that board files we just got IIO
devices with static order so that we knew exactly what iio:device0 is.
Now with device tree that order is not so static anymore especially when
using device overlays (have not yet tried that thou). If there would be
deferred probe for the device then if we have multiple iio:device's then
those could in theory be in any order.
In example libiio uses iio device index to open the IIO device. So the
problem is to know what iio:device is what.
If we look files under /sys/bus/iio/iio:deviceX. They do not reveal what
device this is (especially if there are multiple device of same type).
There does not seem to be a way to give custom name for the iio device
from device tree that could have been used as a cue.
Device tree aliases kinda sounded a good idea to try. Eg. define adc0
alias and then link it to actual device node in tree.
Aliases could be found under /proc/device-tree/aliases. Looking at it
shows what device tree node it is. However there does not seem to be
actual link from any /proc/device-tree entries to kernel drivers exposed
under sysfs. And even the path components in device tree are not in same
format as in sysfs. So there is no 1:1 mapping possible here.
IIO devices in /sys/bus/iio/iio:deviceX seem to be symlinks to actual
devices under /sys/devices and from there is physical path to the device
and under that the IIO device with the same name as is under /sys/bus/iio.
So in theory we could make a mapping configuration file that specifies
logical name for iio device and then physical parent path for the device
and then find under it iio:device* files to determine what is the iio
device index for this physical device. Then open IIO device with that
index in example with libiio. Sounds a bit complex?
So did we miss something on how this should be defined/accessed or is
there a slight issue here on how to identify iio devices?
Don't know how device tree overlays affect this if we first load device
tree overlay with some configuration and then unload it and load another
one with different configuration.
Thanks,
Vesa Jääskeläinen
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