Date:   Tue, 23 May 2017 17:54:30 +0200
From:   Fabrice Gasnier <fabrice.gasnier@...com>
To:     Rob Herring <robh@...nel.org>
CC:     <jic23@...nel.org>, <linux@...linux.org.uk>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <mark.rutland@....com>, <benjamin.gaignard@...aro.org>,
        <lars@...afoo.de>, <alexandre.torgue@...com>,
        <linux-iio@...r.kernel.org>, <pmeerw@...erw.net>,
        <mcoquelin.stm32@...il.com>, <knaack.h@....de>,
        <benjamin.gaignard@...com>
Subject: Re: [PATCH 1/5] dt-bindings: iio: stm32-adc: add support for STM32H7

On 05/23/2017 05:07 PM, Rob Herring wrote:
> On Fri, May 19, 2017 at 02:45:24PM +0200, Fabrice Gasnier wrote:
>> Document support for STM32H7 Analog to Digital Converter.
>> Main difference is regarding compatible, clock definitions and new
>> features like differential channels support:
>> STM32H7 ADC block has two clock inputs, common clock for all ADCs.
>> One 'bus' clock for registers access, and one optional 'adc' clock
>> for analog circuitry (bus clock may be used for conversions).
>>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...com>
>> ---
>>  .../devicetree/bindings/iio/adc/st,stm32-adc.txt     | 20 ++++++++++++++------
>>  1 file changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt
>> index e35f9f1..9519d2e 100644
>> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt
>> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt
>> @@ -21,11 +21,17 @@ own configurable sequence and trigger:
>>  Contents of a stm32 adc root node:
>>  -----------------------------------
>>  Required properties:
>> -- compatible: Should be "st,stm32f4-adc-core".
>> +- compatible: Should be one of "st,stm32f4-adc-core" or "st,stm32h7-adc-core".
> Reformat this to 1 per line.
Hi Rob,

I'll fix it in v2
>
>>  - reg: Offset and length of the ADC block register set.
>>  - interrupts: Must contain the interrupt for ADC block.
>> -- clocks: Clock for the analog circuitry (common to all ADCs).
>> -- clock-names: Must be "adc".
>> +- clocks: Core can use up to two clocks, depending on part used:
>> +  - "adc" clock: for the analog circuitry, common to all ADCs.
>> +    It's required on stm32f4.
>> +    It's optional on stm32h7, bus clock will be used by default if not set.
> The clocks listed should be all connections present, not policy as to 
> what clock you want to use for conversions.
Shall I only mention it's optional on stm32h7 ?
(e.g. remove "bus clock will...")

>
>> +  - "bus" clock: for registers access, common to all ADCs.
>> +    It's unused on stm32f4.
> s/unused/not present/
I'll fix it in v2

>
>> +    It's required on stm32h7.
>> +- clock-names: Must be "adc" and/or "bus" depending on part used.
>>  - interrupt-controller: Identifies the controller node as interrupt-parent
>>  - vref-supply: Phandle to the vref input analog reference voltage.
>>  - #interrupt-cells = <1>;
>> @@ -42,14 +48,16 @@ An ADC block node should contain at least one subnode, representing an
>>  ADC instance available on the machine.
>>  
>>  Required properties:
>> -- compatible: Should be "st,stm32f4-adc".
>> +- compatible: Should be one of "st,stm32f4-adc" or "st,stm32h7-adc".
> One per line.
I'll fix it in v2

>
>>  - reg: Offset of ADC instance in ADC block (e.g. may be 0x0, 0x100, 0x200).
>> -- clocks: Input clock private to this ADC instance.
>> +- clocks: Input clock private to this ADC instance. It's required only on
>> +  stm32f4, that has per instance clock input for registers access.
> Does the h7 simply have the same parent connected to all ADC instances 
> or really doesn't have a per instance clock? For the former case, you 
> should still have a clock, but just all be the same parent.
It's the second case. There's no per instance clock.
Do you want me to rephrase a little ?
e.g. like it's required on stm32f4 and not present on stm32h7 ?

Please advise,
Thanks for reviewing,
Fabrice

>
>>  - interrupt-parent: Phandle to the parent interrupt controller.
>>  - interrupts: IRQ Line for the ADC (e.g. may be 0 for adc@0, 1 for adc@100 or
>>    2 for adc@200).
>>  - st,adc-channels: List of single-ended channels muxed for this ADC.
>> -  It can have up to 16 channels, numbered from 0 to 15 (resp. for in0..in15).
>> +  It can have up to 16 channels on stm32f4 or 20 channels on stm32h7, numbered
>> +  from 0 to 15 or 19 (resp. for in0..in15 or in0..in19).
>>  - #io-channel-cells = <1>: See the IIO bindings section "IIO consumers" in
>>    Documentation/devicetree/bindings/iio/iio-bindings.txt
>>  
>> -- 
>> 1.9.1
>>
>>
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>> linux-arm-kernel@...ts.infradead.org
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