Re: [PATCH v2 4/4] iio: documentation: Document scd4x calibration use
From: Jonathan Cameron <jic23@kernel.org>
Date: 2021-09-19 16:47:55
Also in:
linux-iio, lkml
On Mon, 13 Sep 2021 10:00:20 +0200 Roan van Dijk [off-list ref] wrote:
Add entries from Documentation/ABI/testing/sysfs-bus-iio-scd30 to Documentation/ABI/testing/sysfs-bus-iio. The attributes of the scd4x and scd30 are common. Remove Documentation/ABI/testing/sysfs-bus-iio-scd30. Signed-off-by: Roan van Dijk <roan@protonic.nl>
Hi Roan, Great to move these, but there is a bit too much 'specific' detail in here reflecting the scd30. We either need to make the descriptions more generic or state some parts are only true for that device. Some suggestions inline. Make sure they also apply to your new driver. Thanks, Jonathan
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--- Documentation/ABI/testing/sysfs-bus-iio | 35 +++++++++++++++++++ Documentation/ABI/testing/sysfs-bus-iio-scd30 | 34 ------------------ 2 files changed, 35 insertions(+), 34 deletions(-) delete mode 100644 Documentation/ABI/testing/sysfs-bus-iio-scd30diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio index 6ad47a67521c..56492c564f72 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio +++ b/Documentation/ABI/testing/sysfs-bus-iio@@ -1957,3 +1957,38 @@ Description: Specify the percent for light sensor relative to the channel absolute value that a data field should change before an event is generated. Units are a percentage of the prior reading. + +What: /sys/bus/iio/devices/iio:deviceX/calibration_auto_enable +Date: June 2020 +KernelVersion: 5.8 +Contact: linux-iio@vger.kernel.org +Description: + Contaminants build-up in the measurement chamber or optical + elements deterioration leads to sensor drift.
Given this is a top level ABI doc, we don't know it is sensor with a measurement chamber or that it's optical. This might be an ADC. We could make this an example. Some sensors have the ability to apply auto calibration at runtime. For example, it may be necessary to compensate for contaminant build-up in a measurement chamber or optical element deterioration that would otherwise lead to sensor drift. Writing 1 or 0 to this attribute will respectively activate or deactivate this auto calibration function. Upon reading, the current status is returned.
+ + One can compensate for sensor drift by using automatic self + calibration procedure (asc). + + Writing 1 or 0 to this attribute will respectively activate or + deactivate asc. + + Upon reading current asc status is returned. + +What: /sys/bus/iio/devices/iio:deviceX/calibration_forced_value +Date: June 2020 +KernelVersion: 5.8 +Contact: linux-iio@vger.kernel.org +Description: + Contaminants build-up in the measurement chamber or optical + elements deterioration leads to sensor drift. + + One can compensate for sensor drift by using forced + recalibration (frc). This is useful in case there's known + co2 reference available nearby the sensor.
Remove the c02 specific references from here and have something like Some sensors have the ability to apply a manual calibration using a known measurement value, perhaps obtained from an external reference device. Writing a value to this function will force such a calibration change. For the scd30 the value should be from the range [400 1 2000]. Note that a valid value may only be obtained once it is has been written. Until then any read back of this value should be ignored. Hmm. That last bit is rather ugly. I'd rather we returned an error code if the value had not yet been forced. We should clean that up at some stage and also add an appropriate _available so we don't need to document the range in this file.
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+ + Picking value from the range [400 1 2000] and writing it to the + sensor will set frc. + + Upon reading current frc value is returned. Note that after + power cycling default value (i.e 400) is returned even though + internally sensor had recalibrated itself.diff --git a/Documentation/ABI/testing/sysfs-bus-iio-scd30 b/Documentation/ABI/testing/sysfs-bus-iio-scd30 deleted file mode 100644 index b9712f390bec..000000000000 --- a/Documentation/ABI/testing/sysfs-bus-iio-scd30 +++ /dev/null@@ -1,34 +0,0 @@ -What: /sys/bus/iio/devices/iio:deviceX/calibration_auto_enable -Date: June 2020 -KernelVersion: 5.8 -Contact: linux-iio@vger.kernel.org -Description: - Contaminants build-up in the measurement chamber or optical - elements deterioration leads to sensor drift. - - One can compensate for sensor drift by using automatic self - calibration procedure (asc). - - Writing 1 or 0 to this attribute will respectively activate or - deactivate asc. - - Upon reading current asc status is returned. - -What: /sys/bus/iio/devices/iio:deviceX/calibration_forced_value -Date: June 2020 -KernelVersion: 5.8 -Contact: linux-iio@vger.kernel.org -Description: - Contaminants build-up in the measurement chamber or optical - elements deterioration leads to sensor drift. - - One can compensate for sensor drift by using forced - recalibration (frc). This is useful in case there's known - co2 reference available nearby the sensor. - - Picking value from the range [400 1 2000] and writing it to the - sensor will set frc. - - Upon reading current frc value is returned. Note that after - power cycling default value (i.e 400) is returned even though - internally sensor had recalibrated itself.