| Message ID | 1487177757-19427-2-git-send-email-fabrice.gasnier@st.com |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
On 15/02/17 16:55, Fabrice Gasnier wrote: > Add documentation for 'st,adc-res' dt optional property. > > Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> I'm happy with this, but would like to leave time for a device tree review. Ultimately we may well want to make this a generic property and call it something like adc-resolution but perhaps we need to wait until we have a few more devices supporting setting it via device tree to figure out what the best interface is. It would exactly be a problem to support this as a deprecated binding at that point. Give me a poke if we hear nothing from Rob or Mark for say another week. Thanks, Jonathan > --- > Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt > index 5dfc88e..45f7ff2 100644 > --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt > +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt > @@ -57,6 +57,9 @@ Optional properties: > - dmas: Phandle to dma channel for this ADC instance. > See ../../dma/dma.txt for details. > - dma-names: Must be "rx" when dmas property is being used. > +- st,adc-res: Resolution (bits) to use for conversions. Must match device > + available resolutions (e.g. can be 6, 8, 10 or 12 on stm32f4). Default > + is maximum resolution if unset. > > Example: > adc: adc@40012000 { > @@ -84,6 +87,7 @@ Example: > st,adc-channels = <8>; > dmas = <&dma2 0 0 0x400 0x0>; > dma-names = "rx"; > + st,adc-res = <8>; > }; > ... > other adc child nodes follow... > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 02/19/2017 01:09 PM, Jonathan Cameron wrote: > On 15/02/17 16:55, Fabrice Gasnier wrote: >> Add documentation for 'st,adc-res' dt optional property. >> >> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> > I'm happy with this, but would like to leave time for a device tree review. > > Ultimately we may well want to make this a generic property and call it something > like adc-resolution but perhaps we need to wait until we have a few more devices > supporting setting it via device tree to figure out what the best interface is. > It would exactly be a problem to support this as a deprecated binding at that > point. Hi Jonathan, I agree with you on this... It may be better to have generic property for this, especially if you see that it will come in the near future. May I suggest this prop to be less restrictive, e.g. like resolution-bits as is may also be worth for other device types, e.g. DAC as an example ? > > Give me a poke if we hear nothing from Rob or Mark for say another week. No news yet, but it can wait a little longer. Please advise, Regards, Fabrice > > Thanks, > > Jonathan > >> --- >> Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt >> index 5dfc88e..45f7ff2 100644 >> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt >> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt >> @@ -57,6 +57,9 @@ Optional properties: >> - dmas: Phandle to dma channel for this ADC instance. >> See ../../dma/dma.txt for details. >> - dma-names: Must be "rx" when dmas property is being used. >> +- st,adc-res: Resolution (bits) to use for conversions. Must match device >> + available resolutions (e.g. can be 6, 8, 10 or 12 on stm32f4). Default >> + is maximum resolution if unset. >> >> Example: >> adc: adc@40012000 { >> @@ -84,6 +87,7 @@ Example: >> st,adc-channels = <8>; >> dmas = <&dma2 0 0 0x400 0x0>; >> dma-names = "rx"; >> + st,adc-res = <8>; >> }; >> ... >> other adc child nodes follow... >> > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 24/02/17 16:04, Fabrice Gasnier wrote: > On 02/19/2017 01:09 PM, Jonathan Cameron wrote: >> On 15/02/17 16:55, Fabrice Gasnier wrote: >>> Add documentation for 'st,adc-res' dt optional property. >>> >>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> >> I'm happy with this, but would like to leave time for a device tree review. >> >> Ultimately we may well want to make this a generic property and call it something >> like adc-resolution but perhaps we need to wait until we have a few more devices >> supporting setting it via device tree to figure out what the best interface is. >> It would exactly be a problem to support this as a deprecated binding at that >> point. > > Hi Jonathan, > > I agree with you on this... It may be better to have generic property > for this, especially if you see that it will come in the near future. > May I suggest this prop to be less restrictive, e.g. like > resolution-bits as is may also be worth for other device types, e.g. > DAC as an example ?> Sure, why not - no loss of meaning here. We may never use it for anything else but that doesn't matter. >> >> Give me a poke if we hear nothing from Rob or Mark for say another week. > > No news yet, but it can wait a little longer. Rob / Mark, can you take a look at this if you have time? Thanks, Jonathan > > Please advise, > Regards, > Fabrice > >> >> Thanks, >> >> Jonathan >> >>> --- >>> Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt >>> index 5dfc88e..45f7ff2 100644 >>> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt >>> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt >>> @@ -57,6 +57,9 @@ Optional properties: >>> - dmas: Phandle to dma channel for this ADC instance. >>> See ../../dma/dma.txt for details. >>> - dma-names: Must be "rx" when dmas property is being used. >>> +- st,adc-res: Resolution (bits) to use for conversions. Must match device >>> + available resolutions (e.g. can be 6, 8, 10 or 12 on stm32f4). Default >>> + is maximum resolution if unset. >>> >>> Example: >>> adc: adc@40012000 { >>> @@ -84,6 +87,7 @@ Example: >>> st,adc-channels = <8>; >>> dmas = <&dma2 0 0 0x400 0x0>; >>> dma-names = "rx"; >>> + st,adc-res = <8>; >>> }; >>> ... >>> other adc child nodes follow... >>> >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Feb 24, 2017 at 05:04:45PM +0100, Fabrice Gasnier wrote: > On 02/19/2017 01:09 PM, Jonathan Cameron wrote: > > On 15/02/17 16:55, Fabrice Gasnier wrote: > > > Add documentation for 'st,adc-res' dt optional property. > > > > > > Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> > > I'm happy with this, but would like to leave time for a device tree review. > > > > Ultimately we may well want to make this a generic property and call it something > > like adc-resolution but perhaps we need to wait until we have a few more devices > > supporting setting it via device tree to figure out what the best interface is. > > It would exactly be a problem to support this as a deprecated binding at that > > point. > > Hi Jonathan, > > I agree with you on this... It may be better to have generic property > for this, especially if you see that it will come in the near future. > May I suggest this prop to be less restrictive, e.g. like resolution-bits as > is may also be worth for other device types, e.g. DAC as an example ? Yes, please make this a commmon property. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 02/25/2017 04:11 PM, Jonathan Cameron wrote: > On 24/02/17 16:04, Fabrice Gasnier wrote: >> On 02/19/2017 01:09 PM, Jonathan Cameron wrote: >>> On 15/02/17 16:55, Fabrice Gasnier wrote: >>>> Add documentation for 'st,adc-res' dt optional property. >>>> >>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> >>> I'm happy with this, but would like to leave time for a device tree review. >>> >>> Ultimately we may well want to make this a generic property and call it something >>> like adc-resolution but perhaps we need to wait until we have a few more devices >>> supporting setting it via device tree to figure out what the best interface is. >>> It would exactly be a problem to support this as a deprecated binding at that >>> point. >> >> Hi Jonathan, >> >> I agree with you on this... It may be better to have generic property >> for this, especially if you see that it will come in the near future. >> May I suggest this prop to be less restrictive, e.g. like >> resolution-bits as is may also be worth for other device types, e.g. >> DAC as an example ?> > Sure, why not - no loss of meaning here. We may never use it for anything > else but that doesn't matter. Hi Jonathan, Following Rob's comment, how you see such a common property can be integrated. Currently I don't see much devices are doing this. Do you have ideas or preferences on this ? - Do you think replacing 'st,adc-res' by 'resolution-bits' in current patchset is enough for now ? - Or do I need to add dt parsing routine in IIO core, e.g. as simple as of_iio_get_resolution(), or something like this ? Or parsing routine that may fill in a common properties structure (but only resolution will be there from the start)... Please let me know. Thanks, Fabrice >>> >>> Give me a poke if we hear nothing from Rob or Mark for say another week. >> >> No news yet, but it can wait a little longer. > Rob / Mark, can you take a look at this if you have time? > > Thanks, > > Jonathan >> >> Please advise, >> Regards, >> Fabrice >> >>> >>> Thanks, >>> >>> Jonathan >>> >>>> --- >>>> Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt | 4 ++++ >>>> 1 file changed, 4 insertions(+) >>>> >>>> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt >>>> index 5dfc88e..45f7ff2 100644 >>>> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt >>>> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt >>>> @@ -57,6 +57,9 @@ Optional properties: >>>> - dmas: Phandle to dma channel for this ADC instance. >>>> See ../../dma/dma.txt for details. >>>> - dma-names: Must be "rx" when dmas property is being used. >>>> +- st,adc-res: Resolution (bits) to use for conversions. Must match device >>>> + available resolutions (e.g. can be 6, 8, 10 or 12 on stm32f4). Default >>>> + is maximum resolution if unset. >>>> >>>> Example: >>>> adc: adc@40012000 { >>>> @@ -84,6 +87,7 @@ Example: >>>> st,adc-channels = <8>; >>>> dmas = <&dma2 0 0 0x400 0x0>; >>>> dma-names = "rx"; >>>> + st,adc-res = <8>; >>>> }; >>>> ... >>>> other adc child nodes follow... >>>> >>> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 02/28/2017 09:21 AM, Fabrice Gasnier wrote: > On 02/25/2017 04:11 PM, Jonathan Cameron wrote: >> On 24/02/17 16:04, Fabrice Gasnier wrote: >>> On 02/19/2017 01:09 PM, Jonathan Cameron wrote: >>>> On 15/02/17 16:55, Fabrice Gasnier wrote: >>>>> Add documentation for 'st,adc-res' dt optional property. >>>>> >>>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> >>>> I'm happy with this, but would like to leave time for a device tree review. >>>> >>>> Ultimately we may well want to make this a generic property and call it >>>> something >>>> like adc-resolution but perhaps we need to wait until we have a few more >>>> devices >>>> supporting setting it via device tree to figure out what the best >>>> interface is. >>>> It would exactly be a problem to support this as a deprecated binding at >>>> that >>>> point. >>> >>> Hi Jonathan, >>> >>> I agree with you on this... It may be better to have generic property >>> for this, especially if you see that it will come in the near future. >>> May I suggest this prop to be less restrictive, e.g. like >>> resolution-bits as is may also be worth for other device types, e.g. >>> DAC as an example ?> >> Sure, why not - no loss of meaning here. We may never use it for anything >> else but that doesn't matter. > > Hi Jonathan, > > Following Rob's comment, how you see such a common property can be > integrated. Currently I don't see much devices are doing this. > Do you have ideas or preferences on this ? > > - Do you think replacing 'st,adc-res' by 'resolution-bits' in current > patchset is enough for now ? That name would be a bit confusing. Considering that the devicetree describes th capabilities of the hardware this name would suggest that this is the resolution supported by the device. If we want to allow selecting runtime configuration parameters for IIO devices from the devicetree we should probably follow the precedence set by the clock framework and use properties with the 'assigned-' prefix. But to be honest I'm not convinced yet that the whole approach of allowing runtime configuration parameters to be configured via the devicetree is the right approach. Converters and sensors often have a lot of runtime configurable parameters, typically we expose them to the application layer to allow maximum flexibility. Why is the resolution special in this case and should be pre-configured via the devicetree instead? - Lars -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 02/28/2017 09:34 AM, Lars-Peter Clausen wrote: > On 02/28/2017 09:21 AM, Fabrice Gasnier wrote: >> On 02/25/2017 04:11 PM, Jonathan Cameron wrote: >>> On 24/02/17 16:04, Fabrice Gasnier wrote: >>>> On 02/19/2017 01:09 PM, Jonathan Cameron wrote: >>>>> On 15/02/17 16:55, Fabrice Gasnier wrote: >>>>>> Add documentation for 'st,adc-res' dt optional property. >>>>>> >>>>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> >>>>> I'm happy with this, but would like to leave time for a device tree review. >>>>> >>>>> Ultimately we may well want to make this a generic property and call it >>>>> something >>>>> like adc-resolution but perhaps we need to wait until we have a few more >>>>> devices >>>>> supporting setting it via device tree to figure out what the best >>>>> interface is. >>>>> It would exactly be a problem to support this as a deprecated binding at >>>>> that >>>>> point. >>>> >>>> Hi Jonathan, >>>> >>>> I agree with you on this... It may be better to have generic property >>>> for this, especially if you see that it will come in the near future. >>>> May I suggest this prop to be less restrictive, e.g. like >>>> resolution-bits as is may also be worth for other device types, e.g. >>>> DAC as an example ?> >>> Sure, why not - no loss of meaning here. We may never use it for anything >>> else but that doesn't matter. >> >> Hi Jonathan, >> >> Following Rob's comment, how you see such a common property can be >> integrated. Currently I don't see much devices are doing this. >> Do you have ideas or preferences on this ? >> >> - Do you think replacing 'st,adc-res' by 'resolution-bits' in current >> patchset is enough for now ? > > That name would be a bit confusing. Considering that the devicetree > describes th capabilities of the hardware this name would suggest that this > is the resolution supported by the device. > > If we want to allow selecting runtime configuration parameters for IIO > devices from the devicetree we should probably follow the precedence set by > the clock framework and use properties with the 'assigned-' prefix. Hi Lars, This makes sense. Then, do you see 'assigned-resolution-bits' as a better candidate ? Also, do you think listing all devices caps in property like 'resolutions-bits', e.g. 'resolutions-bits = <6 8 10 12>', is suitable/necessary ? > > But to be honest I'm not convinced yet that the whole approach of allowing > runtime configuration parameters to be configured via the devicetree is the > right approach. Converters and sensors often have a lot of runtime > configurable parameters, typically we expose them to the application layer > to allow maximum flexibility. Why is the resolution special in this case and > should be pre-configured via the devicetree instead? As I understand it, currently lots of devices have hard-coded (maximum?) resolution, then exposed to application layer as read only data format. Then resolution depends on HW used (e.g. sensor, converter). Depending on the application board, it may be worth to offer pre-configured intermediate/lower resolution depending on analog sources. Is it ok to offer devicetree pre-configuration ? Best Regards, Fabrice > > - Lars > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 28/02/17 10:14, Fabrice Gasnier wrote: > On 02/28/2017 09:34 AM, Lars-Peter Clausen wrote: >> On 02/28/2017 09:21 AM, Fabrice Gasnier wrote: >>> On 02/25/2017 04:11 PM, Jonathan Cameron wrote: >>>> On 24/02/17 16:04, Fabrice Gasnier wrote: >>>>> On 02/19/2017 01:09 PM, Jonathan Cameron wrote: >>>>>> On 15/02/17 16:55, Fabrice Gasnier wrote: >>>>>>> Add documentation for 'st,adc-res' dt optional property. >>>>>>> >>>>>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> >>>>>> I'm happy with this, but would like to leave time for a device tree review. >>>>>> >>>>>> Ultimately we may well want to make this a generic property and call it >>>>>> something >>>>>> like adc-resolution but perhaps we need to wait until we have a few more >>>>>> devices >>>>>> supporting setting it via device tree to figure out what the best >>>>>> interface is. >>>>>> It would exactly be a problem to support this as a deprecated binding at >>>>>> that >>>>>> point. >>>>> >>>>> Hi Jonathan, >>>>> >>>>> I agree with you on this... It may be better to have generic property >>>>> for this, especially if you see that it will come in the near future. >>>>> May I suggest this prop to be less restrictive, e.g. like >>>>> resolution-bits as is may also be worth for other device types, e.g. >>>>> DAC as an example ?> >>>> Sure, why not - no loss of meaning here. We may never use it for anything >>>> else but that doesn't matter. >>> >>> Hi Jonathan, >>> >>> Following Rob's comment, how you see such a common property can be >>> integrated. Currently I don't see much devices are doing this. >>> Do you have ideas or preferences on this ? >>> >>> - Do you think replacing 'st,adc-res' by 'resolution-bits' in current >>> patchset is enough for now ? >> >> That name would be a bit confusing. Considering that the devicetree >> describes th capabilities of the hardware this name would suggest that this >> is the resolution supported by the device. >> >> If we want to allow selecting runtime configuration parameters for IIO >> devices from the devicetree we should probably follow the precedence set by >> the clock framework and use properties with the 'assigned-' prefix. > > Hi Lars, > > This makes sense. Then, do you see 'assigned-resolution-bits' as a > better candidate ? > Also, do you think listing all devices caps in property like 'resolutions-bits', e.g. 'resolutions-bits = <6 8 10 12>', is > suitable/necessary ? Only suitable / necessary if what the options are is dependent on the hardware in some way that is not adequately described by the compatibility element. > >> >> But to be honest I'm not convinced yet that the whole approach of allowing >> runtime configuration parameters to be configured via the devicetree is the >> right approach. Converters and sensors often have a lot of runtime >> configurable parameters, typically we expose them to the application layer >> to allow maximum flexibility. Why is the resolution special in this case and >> should be pre-configured via the devicetree instead? > To be cynical because it is PITA to change the assumption of it being fixed :) Oh well, another design decision that we got wrong a long time back. > As I understand it, currently lots of devices have hard-coded > (maximum?) resolution, then exposed to application layer as read only > data format. Then resolution depends on HW used (e.g. sensor, > converter). Depending on the application board, it may be worth to > offer pre-configured intermediate/lower resolution depending on > analog sources. Is it ok to offer devicetree pre-configuration ? > Hmm. It is in theory acceptable to put default values that make sense for a given set of hardware in device tree. They are kind of a 'well this will work' state. Make sense if there are states that don't make sense for a given hardware setup. If all states make equally good sense, then perhaps we should look at fixing up the IIO core to handle variable resolution devices. That strikes me as a non trivial exercise, but could probably be done. We'd need to keep the simplicity of the current code for the vast majority of devices, but provide some relatively clean way of changing it when needed. Whilst I'm happy if someone else wants to look at this, it is nowhere near the top of my list! Jonathan > Best Regards, > Fabrice >> >> - Lars >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt index 5dfc88e..45f7ff2 100644 --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt @@ -57,6 +57,9 @@ Optional properties: - dmas: Phandle to dma channel for this ADC instance. See ../../dma/dma.txt for details. - dma-names: Must be "rx" when dmas property is being used. +- st,adc-res: Resolution (bits) to use for conversions. Must match device + available resolutions (e.g. can be 6, 8, 10 or 12 on stm32f4). Default + is maximum resolution if unset. Example: adc: adc@40012000 { @@ -84,6 +87,7 @@ Example: st,adc-channels = <8>; dmas = <&dma2 0 0 0x400 0x0>; dma-names = "rx"; + st,adc-res = <8>; }; ... other adc child nodes follow...
Add documentation for 'st,adc-res' dt optional property. Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> --- Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt | 4 ++++ 1 file changed, 4 insertions(+)