Re: [PATCH v2] ARM: zynq: Add #io-channel-cells to (x)adc node for iio-hwmon

[Lars-Peter Clausen <lars@metafoo.de>]

On 03/16/2017 05:45 PM, Michal Simek wrote:
> On 16.3.2017 17:39, Moritz Fischer wrote:
>> On Thu, Mar 16, 2017 at 9:16 AM, Michal Simek <michal.simek@xilinx.com> wrote:
>>> Hi,
>>>
>>> On 8.3.2017 21:11, Moritz Fischer wrote:
>>>> Fix
>>>>
>>>> OF: /iio_hwmon: could not get #io-channel-cells for
>>>> /amba/adc@f8007100
>>>> OF: /iio_hwmon: could not get #io-channel-cells for
>>>> /amba/adc@f8007100
>>>> OF: /iio_hwmon: could not get #io-channel-cells for
>>>> /amba/adc@f8007100
>>>>
>>>> by adding the #io-channel-cells property.
>>>>
>>>> Signed-off-by: Moritz Fischer <mdf@kernel.org>
>>>> Cc: Michal Simek <michal.simek@xilinx.com>
>>>> Cc: Sören Brinkmann <soren.brinkmann@xilinx.com>
>>>> Cc: Julia Cartwright <julia@ni.com>
>>>> Cc: linux-kernel@vger.kernel.org
>>>> Cc: devicetree@vger.kernel.org
>>>> ---
>>>>
>>>> Changes from v1:
>>>> - fix messed up commit message
>>>> ---
>>>>  arch/arm/boot/dts/zynq-7000.dtsi | 1 +
>>>>  1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/arch/arm/boot/dts/zynq-7000.dtsi b/arch/arm/boot/dts/zynq-7000.dtsi
>>>> index f3ac9bf..98233a8 100644
>>>> --- a/arch/arm/boot/dts/zynq-7000.dtsi
>>>> +++ b/arch/arm/boot/dts/zynq-7000.dtsi
>>>> @@ -72,6 +72,7 @@
>>>>                       interrupts = <0 7 4>;
>>>>                       interrupt-parent = <&intc>;
>>>>                       clocks = <&clkc 12>;
>>>> +                     #io-channel-cells = <1>;
>>>>               };
>>>>
>>>>               can0: can@e0008000 {
>>>>
>>>
>>> I think it will be good to the next step too.
>>> It means also add iio-hwmon node too.
>>>
>>> What do you think?
>>
>> I hadn't put it in there since dts is supposed to describe hw,
>> but obviously putting the actual hwmon in there makes it more useful.
> 
> I had one discussion about this with Grant in past and it is common
> mistake. It is simplification of purpose of dts.
> 

If the iio-hwmon binding had gone through review it would have been rejected.

>>
>> I can resubmit with the hwmon node in there.
> 
> If you grep kernel tree you will see that others are using it too.
> Also there is accepted binding for that that's why I can't see big
> problem with it.

Since this is an application specific binding I wouldn't put it in the
generic DT include file. It's a bit like adding a gpio-key binding for each
of the GPIOs just in case somebody wants to use it.