On Mon, 25 Mar 2024 10:58:51 +0100 Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> wrote: > On 22/03/2024 10:58, Andrej Picej wrote: > > 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 > > > No vendor prefix, so they rather should be generic, not imx93 > specific... But this the binding for imx93, so I don't understand your > statement. Based on my current understanding what we have here is not remotely generic, so standard properties don't make sense (though naming the nxp ones in a consistent fashion with other bindings is useful) I'm not entirely convinced there is a strong argument to support them at all though. Still thinking / gathering info on that. > > > 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. > > You now mix how Linux driver behaves with hardware. Why you cannot > recalibrate later, e.g. when something else is being connected to the > exposed pins? Generally we don't make strong efforts to support dev board use cases where the components wired tend to change. So normally this isn't too much of a concern. Previously, we've tried to support this stuff and it always ends up as a mess because of the crazy range of things that can be wired. Jonathan > > Best regards, > Krzysztof > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
