Re: [PATCH 2/2] dt-bindings: iio: adc: nxp,imx93-adc.yaml: Add calibration properties
From: Andrej Picej
Date: Fri Mar 22 2024 - 05:59:13 EST
On 22. 03. 24 09:14, Krzysztof Kozlowski wrote:
On 22/03/2024 08:39, Andrej Picej wrote:
On 20. 03. 24 13:15, Krzysztof Kozlowski wrote:
On 20/03/2024 13:05, Andrej Picej wrote:
Hi Krzysztof,
On 20. 03. 24 11:26, Krzysztof Kozlowski wrote:
On 20/03/2024 11:04, Andrej Picej wrote:
Document calibration properties and how to set them.
Bindings are before users.
will change patch order when I send a v2.
Please use subject prefixes matching the subsystem. You can get them for
example with `git log --oneline -- DIRECTORY_OR_FILE` on the directory
your patch is touching.
There is no file extension in prefixes.
So: dt-bindings: iio/adc: nxp,imx93-adc: Add calibration properties?
Did you run the command I proposed? I don't see much of "/", but except
that looks good.
Ok noted.
Signed-off-by: Andrej Picej <andrej.picej@xxxxxxxxx>
---
.../bindings/iio/adc/nxp,imx93-adc.yaml | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/Documentation/devicetree/bindings/iio/adc/nxp,imx93-adc.yaml b/Documentation/devicetree/bindings/iio/adc/nxp,imx93-adc.yaml
index dacc526dc695..64958be62a6a 100644
--- a/Documentation/devicetree/bindings/iio/adc/nxp,imx93-adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/nxp,imx93-adc.yaml
@@ -46,6 +46,21 @@ properties:
"#io-channel-cells":
const: 1
+ nxp,calib-avg-en:
+ description:
+ Enable or disable averaging of calibration time.
+ enum: [ 0, 1 ]
+
+ nxp,calib-nr-samples:
+ description:
+ Selects the number of averaging samples to be used during calibration.
+ enum: [ 16, 32, 128, 512 ]
+
+ nxp,calib-t-samples:
+ description:
+ Specifies the sample time of calibration conversions.
+ enum: [ 8, 16, 22, 32 ]
No, use existing, generic properties. Open other bindings for this.
You mean I should use generic properties for the ADC calibration
settings? Is there already something in place? Because as I understand
it, these calib-* values only effect the calibration process of the ADC.
Please take a look at other devices and dtschema. We already have some
properties for this... but maybe they cannot be used?
I did look into other ADC devices, grep across iio/adc, adc bindings
folders and couldn't find anything closely related to what we are
looking for. Could you please point me to the properties that you think
should be used for this?
Indeed, there are few device specific like qcom,avg-samples. We have
though oversampling-ratio, settling-time-us and min-sample-time (which
is not that good because does not use unit suffix).
Ok, these are examples but I think I should not use them, since these
are i.MX93 ADC specific settings, which are used for configuration of
calibration process, and are not related to the standard conversion
process during runtime. Calibration process is the first step that
should be done after every power-on reset.
Then follow up questions:
- nxp,calib-avg-en: Why is it a board-level decision? I would assume
this depends on user choice and what kind of input you have (which could
be board dependent or could be runtime decision).
Not really sure I get your question, so please elaborate if I missed the
point.
This is a user choice, to enable or disable the averaging function in
calibration, but this is a board-level decision, probably relates on
external ADC regulators and input connections. The same options are used
for every ADC channel and this can not be a runtime decision, since
calibration is done before the ADC is even registered.
- nxp,calib-t-samples: what does it mean? Time is expressed in time
units, but there is nothing about units in the property name.
You are right, basically this is "time" in cycles of AD_CLK. I should at
least add that to the property description.
Best regards,
Andrej Picej