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Message-ID: <ZHU2Khf84nbLW7Gg@surfacebook>
Date: Tue, 30 May 2023 02:32:58 +0300
From: andy.shevchenko@...il.com
To: George Stark <gnstark@...rdevices.ru>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
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Subject: Re: [PATCH v2] meson saradc: add iio device attrib to switch channel
7 mux
Mon, May 29, 2023 at 01:31:40AM +0300, George Stark kirjoitti:
> On 5/28/23 13:46, Andy Shevchenko wrote:
> > On Sun, May 28, 2023 at 12:48:54AM +0300, George Stark wrote:
...
> > > + if (index >= ARRAY_SIZE(chan7_vol))
> > > + index = ARRAY_SIZE(chan7_vol) - 1;
> > I think this is incorrect and prone to error in the future in case this array
> > will be extended. What I would expect is to return something like "unknown".
>
> I agree this part is unclean. Actually the register's last 3 (out of 8)
> possible values are stand for the same mux input "ch7_input". So
> theoretically we can read from register a value out of array bounds. There
> should be a comment at least.
You can add there in the array to extend it up to 8 entries, so it will be
clear. And for the rest you will return unknown / unsupported / etc.
...
> > > +static const char * const chan7_vol[] = {
> > > + "gnd",
> > > + "vdd/4",
> > > + "vdd/2",
> > > + "vdd*3/4",
> > > + "vdd",
> > > + "ch7_input",
> > > +};
> About the question of naming mux inputs from the other letter (vdd/2 vs
> 0.5Vdd etc).
> While I fully agree with you that point is better than slash but mixing
> letter cases... should we?
What's wrong with that?
> e.g. this is how iio_info output looks like now:
> ...
> voltage7: (input)
> 3 channel-specific attributes found:
> attr 0: mean_raw value: 0
> attr 1: raw value: 1
> attr 2: scale value: 0.439453125
> 4 device-specific attributes found:
> attr 0: chan7_mux value: gnd
> attr 1: chan7_mux_available value: gnd vdd/4 vdd/2 vdd*3/4
> vdd ch7_input
> attr 2: current_timestamp_clock value: realtime
>
> attr 3: waiting_for_supplier value: 0
>
> or naming with Jonathan's approach
> /sys/devices/platform/soc/fe000000.bus/fe002c00.adc/iio:device0/in_voltage_0.5vdd_raw
See the alternative I proposed is to have _ delimiter. But that might make
parsing a bit harder in user space.
--
With Best Regards,
Andy Shevchenko
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