[PATCH 1/1] Documentation: ABI: IIO: Re-add filter_type/filter_mode

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The ad4130 driver exports in_voltageY-voltageZ_filter_mode and
in_voltage-voltage_filter_mode_available attributes to user space.
The ad7779 driver exports filter_type and filter_type_available.
Add (back again) documentation for filter_type/filter_mode attributes.

Fixes: 01bb12922b60 ("Documentation: ABI: added filter mode doc in sysfs-bus-iio")
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@xxxxxxxxxx>
---
Digressing a bit away from the specific ABI used by ad4130 and ad7779,
the sinc3/4/5 filters are called `filter_mode` in ad4130 driver while other
drivers (ad7779, ad7124, ad7768-1) call sinc3/4/5 filters a `filter_type`.
Datasheets use the term `filter type`.

Depending on the particular ADC chip/design, the sinc3/4/5 filter configuration
may have an impact on the output data rate (ODR) (which is equivalent to the
sampling frequency for SAR ADCs - `sampling_frequency` ABI), 3dB cutoff
frequency of the filter (`_low_pass_3db_frequency` attributes), or settling
time.

ad7768-1 sets sinc3/4/5 according to the sampling_frequency attribute. No
filter_type attribute.

ad7173 sets the filter_type according to sampling_frequency too, though it
looks like support for only one filter type is implemented.

ad7124 sets sinc3/4/5 filters according to a filter_low_pass_3db_frequency
attribute so it doesn't export filter type attributes to user space.
Missing `in_voltageY-voltageZ_filter_low_pass_3db_frequency` documentation?
follow up patch?

 Documentation/ABI/testing/sysfs-bus-iio | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index f83bd6829285..704c9033cb5b 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -2268,6 +2268,20 @@ Description:
 		An example format is 16-bytes, 2-digits-per-byte, HEX-string
 		representing the sensor unique ID number.
 
+What:		/sys/bus/iio/devices/iio:deviceX/filter_type
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY-voltageZ_filter_mode
+voltageY_filter_type_available
+KernelVersion:	6.1
+Contact:	linux-iio@xxxxxxxxxxxxxxx
+Description:
+		Set the filter mode of the channel. When the filter mode
+		changes, the in_voltageY-voltageZ_sampling_frequency and
+		in_voltageY-voltageZ_sampling_frequency_available attributes
+		might also change to accommodate the new filter mode.
+		If the current sampling frequency is out of range for the new
+		filter mode, the sampling frequency will be changed to the
+		closest valid one.
+
 What:		/sys/bus/iio/devices/iio:deviceX/filter_type_available
 What:		/sys/bus/iio/devices/iio:deviceX/in_voltage-voltage_filter_mode_available
 KernelVersion:	6.1

base-commit: 9dd2270ca0b38ee16094817f4a53e7ba78e31567
prerequisite-patch-id: 3370db9ec1e67ba97b55607f445ff37c60929668
prerequisite-patch-id: d686dd309e1d3d39d038613f514e58ff5893ae42
prerequisite-patch-id: c832285d7bcc22433f2314a144566aa9437fd5da
prerequisite-patch-id: 3f758a121e36edd43789e80379ff81beeb2d75ce
prerequisite-patch-id: 0ef36ec4d6cf23f08bdb3bc4399ced2561a2a69b
prerequisite-patch-id: c8e7f0e10a2630bd0029ee160f8dfc3f742378ba
prerequisite-patch-id: 5e85d52a87f2a833893eeeac5d1651bda46d0931
prerequisite-patch-id: cd75aba06cf77f8cd398dc7d0c33d94e1277d1f3
prerequisite-patch-id: b813c25db823f1b02d0e9005188d41c0d89eb291
prerequisite-patch-id: 024ac23a16e45e802b70afe9bc464d1caeb41fcc
prerequisite-patch-id: bc084c859bfa93c5764e656bbcbfd4d14e031299
prerequisite-patch-id: 51ebb591fbbb3535899332ce1b106a3f8d6497da
prerequisite-patch-id: 2b396d1069227fee1c5a7bcf33bc63a56681441b
prerequisite-patch-id: c00b841cea6e331e19fb1f31beae831572bce4f5
prerequisite-patch-id: 4fe5fcebfeb745a83a7054390a304a1e250d74d1
prerequisite-patch-id: 461cce4f81f88bbec71580c0743b8970a504899c
prerequisite-patch-id: 59cf79cfa5f091815f578aad884ba0e3f9ae2175
prerequisite-patch-id: d48f6e531e64ee7797890e9f36f849f881884f1a
prerequisite-patch-id: 5f48c69023ecae6b3de595c9a209d1c4d65b5ba2
prerequisite-patch-id: 73e2fc3be282880231105142342b47b00b23ab6d
prerequisite-patch-id: d71deacf6bb4e90e8059a12a94ade36866729fa0
prerequisite-patch-id: 6173a25ddf92a3d1446923d9e87b15642b761034
prerequisite-patch-id: 5b248ee02cc148eeea4f01c435e701b74bc07c60
prerequisite-patch-id: 9fa4f11d62ba0e1ef9f3ca08ef1ee5c1f0711038
prerequisite-patch-id: 6cf99f094cfa8d984a1c1cab8813d1078ee48f05
prerequisite-patch-id: b42c4bf1ce430dccca920f942c6040f641c8307e
-- 
2.45.2





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