| Message ID | 1500381332-17086-3-git-send-email-fabrice.gasnier@st.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 18 Jul 2017 14:35:31 +0200 Fabrice Gasnier <fabrice.gasnier@st.com> 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@st.com> 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 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 {
On 07/23/2017 12:53 PM, Jonathan Cameron wrote: > On Tue, 18 Jul 2017 14:35:31 +0200 > Fabrice Gasnier <fabrice.gasnier@st.com> 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@st.com> > > 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' ? 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 { >
On Mon, 24 Jul 2017 09:55:37 +0200 Fabrice Gasnier <fabrice.gasnier@st.com> wrote: > On 07/23/2017 12:53 PM, Jonathan Cameron wrote: > > On Tue, 18 Jul 2017 14:35:31 +0200 > > Fabrice Gasnier <fabrice.gasnier@st.com> 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@st.com> > > > > 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@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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 {
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@st.com> --- Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt | 5 +++++ 1 file changed, 5 insertions(+)