On Sun, 28 May 2023 16:22:57 +0100 Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > On Wed, 24 May 2023 14:36:28 +0300 > Maxim Kiselev <bigunclemax@xxxxxxxxx> wrote: > > > Hi Andre, > > > > thanks for you comments > > > > > This may sound kind of obvious, but wouldn't it be easier to model this > > > with one compatible string, and have the number of channels as a DT > > > property? > > > > Yes, I completely agree that using separate config for each SoCs is looks > > overcomplicated because the only difference is the number of channels. > > I thought about a DT property with channels number but I didn't find > > another ADC driver with the same approach (except i2c ADC's with child nodes). > If you are 100% sure that that devices are either > 1) Detectable at runtime > 2) Identical in functionality. > > So that in neither case will any changes on driver support expose differences > in the future then a single compatible is fine. > > The back up is that you use fallback compatibles - list more than one. > Whilst it doesn't matter (as no differences found) the driver can use > the first one. If differences become apparent later, others may be used. > > I'm not however keen on a simple channel count parameter. If you want > to go that way, it's better to provide the fine control of individual channel > child nodes (see Documentation/devicetree/bindings/iio/adc/adc.yaml) > > That way the control is on which channels are wired to something useful, rather > than whether the device can read them or not (which is pointless if no one > wired them up. Another thing to note is that with generic compatibles you loose the ability to have the dt-schmema validate that sets of parameters make sense. If it's just the channels available that may not matter however. > > > > > > > Or, alternatively, using iio/multiplexer/io-channel-mux.yaml, since it's > > > only one ADC anyway? > > I'm sorry, I didn't quite understand what you're suggesting. > > That's normally only used for a separate MUX where we need a separate driver > to handle it. If used on a device like this it would expose additional complexity > to userspace with no benefits in generality etc. > > > > > > And btw: it seems that the T507 (the H616 die with a different pinout) has > > > the same IP, with four channels: > > > http://dl.linux-sunxi.org/T507/ > > > > Oh, thanks for pointing that. I'll add it to the list in the next version. >
