This patch series fixes some issues found by tests on our Zynq-7020
board; the issues usually result in incorrect voltage readings:
[1/5] iio: adc: xilinx: Fix register addresses
[2/5] iio: adc: xilinx: Fix "vccaux" channel .address
[3/5] iio: adc: xilinx: Fix VREFP scale
[4/5] iio: adc: xilinx: Fix VREFN sign
[5/5] iio: adc: xilinx: Set .datasheet_name instead of .extend_name
About [1]: The register addresses in question are currently not used by
the driver, but we do use them for extended tests. (I might provide a
patch to support lowest/highest values another time; see also [5].)
About [3], [4]: The transfer functions for VREFP and VREFN are
vrefp = unsigned(code) * 3.0 / 4096
vrefn = signed(code) * 1.0 / 4096
I know it's not consistent, but that's what UG480 says ... VREFP = 1.25
definitely needs the factor 3.0 to get reasonable values (a factor 1.0
will never get you more than 1.0V). As for VREFN = 0V, we did actually
see negative values on our boards.
About [5]: This may be a matter of debate on the IIO list, but I didn't
get the impression that extensions are intended to be used that way.
.extend_name = "vccint" means that the sysfs node names are
in_voltage0_vccint_raw/_scale, which is a bit unexpected. I would
rather see them called just in_voltage0_*, and reserve extensions for
things like in_voltage0_lowest_* and in_voltage0_highest_* (MIN_VCCINT,
MAX_VCCINT) -- that's what we do in our project.
Note that .extend_name = "vccint", "vccaux", ... also has the side
effect of creating the sysfs nodes vccint_sampling_frequency,
vccaux_sampling_frequency, ... [due to .info_mask_shared_by_all =
BIT(IIO_CHAN_INFO_SAMP_FREQ)], which is probably not desired.
Best regards,
Thomas Betker
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