On Mon, 24 Jul 2017 09:55:37 +0200 Fabrice Gasnier <fabrice.gasnier@xxxxxx> wrote: > On 07/23/2017 12:53 PM, Jonathan Cameron wrote: > > On Tue, 18 Jul 2017 14:35:31 +0200 > > Fabrice Gasnier <fabrice.gasnier@xxxxxx> wrote: > > > >> STM32 ADC allows each channel to be sampled with a different sampling > >> time. There's an application note that deals with this: 'How to get > >> the best ADC accuracy in STM32...' It basically depends on analog input > >> signal electrical properties (depends on board). > >> > >> Add optional 'min-sample-time' property so this can be tuned in dt. > >> > >> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx> > > > > This isn't yet very standard, so I think it needs a manufacturer > > prefix, e.g. st,min-sample-time. Also convention is I believe > > to include the units as part of the naming where appropriate. > > > > Hence st,min-sample-time-nsecs > > Hi Jonathan, > > I originally used st,... form, when writing this patch, until I found > out there's 'min-sample-time' in vf610 adc dt-bindings: > - Documentation/devicetree/bindings/iio/adc/vf610-adc.txt > It looks like to me very similar. > > I also agree it misses '-nsecs' units. Sure, I can use your suggestion > above... > > Please can you just confirm if I should use same property as vf610 adc, > or 'st,min-sample-time-nsecs' ? st,min-sample-time-nsecs. We might well add a generic option in future, but the burden of supporting this old one will be trivial anyway so not a problem. Jonathan > > Thanks for reviewing, > Best regards, > Fabrice > > > > > Otherwise, seems good to me. > > > > Jonathan > >> --- > >> Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt | 5 +++++ > >> 1 file changed, 5 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt > >> index 8310073..9cd964b 100644 > >> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt > >> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt > >> @@ -74,6 +74,11 @@ Optional properties: > >> * can be 6, 8, 10 or 12 on stm32f4 > >> * can be 8, 10, 12, 14 or 16 on stm32h7 > >> Default is maximum resolution if unset. > >> +- min-sample-time: Minimum sampling time in nanoseconds. > >> + Depending on hardware (board) e.g. high/low analog input source impedance, > >> + fine tune of ADC sampling time may be recommended. > >> + This can be either one value or an array that matches 'st,adc-channels' list, > >> + to set sample time resp. for all channels, or independently for each channel. > >> > >> Example: > >> adc: adc@40012000 { > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html