On 02/25/2017 04:11 PM, Jonathan Cameron wrote:

On 24/02/17 16:04, Fabrice Gasnier wrote:

quoted

On 02/19/2017 01:09 PM, Jonathan Cameron wrote:

quoted

On 15/02/17 16:55, Fabrice Gasnier wrote:

quoted

Add documentation for 'st,adc-res' dt optional property.

Signed-off-by: Fabrice Gasnier <redacted>

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

quoted

quoted

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

quoted

Please advise,
Regards,
Fabrice

quoted

Thanks,

Jonathan

quoted

---
 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 at 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...

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