[PATCH v7 2/5] ABI: sysfs-bus-iio: Disambiguate usage for filter_type "none"

[Ben Collins <bcollins@kernel.org>]

When a filter_type is "none", there really is no useful information that
can be presented from sampling and frequency attributes.

This is especially true when the driver supports more than one
filter_type, since the information would be ambiguous.

Suggest returning IIO_VAL_EMPTY for this case.

Signed-off-by: Ben Collins <bcollins@kernel.org>
---
 Documentation/ABI/testing/sysfs-bus-iio | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 7e31b8cd49b32ea5b58bd99afc2e8105314d7a39..df42a4040530ee96096b998bebc8a08b4fb2d78f 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -2276,7 +2276,11 @@ Description:
 		Reading returns a list with the possible filter modes. Options
 		for the attribute:
 
-		* "none" - Filter is disabled/bypassed.
+		* "none" - Filter is disabled/bypassed. When set in the
+		  filter_type attribute, a driver should return IIO_VAL_EMPTY
+		  when reading sampling and frequency related attributes of
+		  this filter, and return -EINVAL when trying to write these
+		  attributes.
 		* "sinc1" - The digital sinc1 filter. Fast 1st
 		  conversion time. Poor noise performance.
 		* "sinc3" - The digital sinc3 filter. Moderate 1st

-- 
2.39.5