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Message-ID: <4734e915-9ea7-4e65-a9ef-bc1e88c40e76@foss.st.com>
Date: Thu, 20 Jun 2024 10:03:44 +0200
From: Olivier MOYSAN <olivier.moysan@...s.st.com>
To: Conor Dooley <conor@...nel.org>
CC: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>,
Jonathan Cameron
<jic23@...nel.org>,
Lars-Peter Clausen <lars@...afoo.de>, Rob Herring
<robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley
<conor+dt@...nel.org>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre
Torgue <alexandre.torgue@...s.st.com>,
Fabrice Gasnier
<fabrice.gasnier@...s.st.com>,
<alsa-devel@...a-project.org>, <linux-iio@...r.kernel.org>,
<devicetree@...r.kernel.org>,
<linux-stm32@...md-mailman.stormreply.com>,
<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/8] dt-bindings: iio: dfsdm: move to backend framework
Hi Conor,
On 6/18/24 20:10, Conor Dooley wrote:
> On Tue, Jun 18, 2024 at 06:08:30PM +0200, Olivier Moysan wrote:
>> Change the DFSDM binding to use the new IIO backend framework,
>> along with the adoption of IIO generic channels.
>> This binding change allows to add scaling support to the DFSDM.
>>
>> Keep the legacy binding as deprecated for backward compatibility.
>>
>> The io-backends property is supported only in generic IIO channel
>> binding.
>>
>> - Channel description with the generic binding (Audio and Analog):
>>
>> Properties supersed by generic properties:
>> st,adc-channels: becomes "reg" property in channel node
>> st,adc-channel-names: becomes "label" property in channel node
>> Properties moved to channel child node:
>> st,adc-channel-types, st,adc-channel-clk-src, st,adc-alt-channel
>>
>> - Analog binding:
>>
>> DFSDM filter channel is configured as an IIO backend consumer.
>> Add io-backends property in channel child nodes.
>>
>> DFSDM is no more configured as a channel consumer from SD modulator.
>> Use of io-channels in DFSDM node is deprecated.
>>
>> - Audio binding:
>>
>> DFSDM audio DAI is configured as a channel consumer from DFSDM filter.
>> No change compare to legacy.
>>
>> Signed-off-by: Olivier Moysan <olivier.moysan@...s.st.com>
>> ---
>> .../bindings/iio/adc/st,stm32-dfsdm-adc.yaml | 158 +++++++++++++++++-
>> 1 file changed, 152 insertions(+), 6 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
>> index c1b1324fa132..dd414bab74c1 100644
>> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
>> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
>> @@ -102,9 +102,11 @@ patternProperties:
>> items:
>> minimum: 0
>> maximum: 7
>> + deprecated: true
>>
>> st,adc-channel-names:
>> description: List of single-ended channel names.
>> + deprecated: true
>>
>> st,filter-order:
>> description: |
>> @@ -118,6 +120,12 @@ patternProperties:
>> "#io-channel-cells":
>> const: 1
>>
>> + '#address-cells':
>> + const: 1
>> +
>> + '#size-cells':
>> + const: 0
>> +
>> st,adc-channel-types:
>> description: |
>> Single-ended channel input type.
>> @@ -128,6 +136,7 @@ patternProperties:
>> items:
>> enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
>> $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>> + deprecated: true
>>
>> st,adc-channel-clk-src:
>> description: |
>> @@ -139,6 +148,7 @@ patternProperties:
>> items:
>> enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
>> $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>> + deprecated: true
>>
>> st,adc-alt-channel:
>> description:
>> @@ -147,6 +157,7 @@ patternProperties:
>> If not set, channel n is connected to SPI input n.
>> If set, channel n is connected to SPI input n + 1.
>> type: boolean
>> + deprecated: true
>>
>> st,filter0-sync:
>> description:
>> @@ -165,11 +176,65 @@ patternProperties:
>> - compatible
>> - reg
>> - interrupts
>> - - st,adc-channels
>> - - st,adc-channel-names
>> - st,filter-order
>> - "#io-channel-cells"
>>
>> + patternProperties:
>> + "^channel@([0-9]|1[0-9])$":
>> + type: object
>> + $ref: adc.yaml
>> + description: Represents the external channels which are connected to the DFSDM.
>> +
>> + properties:
>> + reg:
>> + items:
>> + minimum: 0
>> + maximum: 8
>> +
>> + label:
>> + description:
>> + Unique name to identify which channel this is.
>> +
>> + st,adc-channel-types:
>> + description: |
>> + Single-ended channel input type.
>> + - "SPI_R": SPI with data on rising edge (default)
>> + - "SPI_F": SPI with data on falling edge
>> + - "MANCH_R": manchester codec, rising edge = logic 0, falling edge = logic 1
>> + - "MANCH_F": manchester codec, rising edge = logic 1, falling edge = logic 0
>> + items:
>> + enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
>> + $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>
> Why is this an array? And why is the property plural? Can a channel have
> more than one type?
>
You are right. In channel node context, this property is no more an
array. It has to be managed as a single string (This is already the case
in the driver). I will change the type in binding and the name, to
reflect this.
>> +
>> + st,adc-channel-clk-src:
>> + description: |
>> + Conversion clock source.
>> + - "CLKIN": external SPI clock (CLKIN x)
>> + - "CLKOUT": internal SPI clock (CLKOUT) (default)
>> + - "CLKOUT_F": internal SPI clock divided by 2 (falling edge).
>> + - "CLKOUT_R": internal SPI clock divided by 2 (rising edge).
>> + items:
>> + enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
>> + $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>
> Ditto here, but s/type/clock source/
>
Same here.
> Thanks,
> Conor.
>
>> +
>> + st,adc-alt-channel:
>> + description:
>> + Must be defined if two sigma delta modulators are
>> + connected on same SPI input.
>> + If not set, channel n is connected to SPI input n.
>> + If set, channel n is connected to SPI input n + 1.
>> + type: boolean
>> +
>> + io-backends:
>> + description:
>> + From common IIO binding.
>
> Drop this from the description.
>
>> Used to pipe external sigma delta
>> + modulator or internal ADC backend to DFSDM channel.
>> +
>> + required:
>> + - reg
>> +
>> + additionalProperties: false
>> +
>> allOf:
>> - if:
>> properties:
>> @@ -199,9 +264,19 @@ patternProperties:
>> description:
>> From common IIO binding. Used to pipe external sigma delta
>> modulator or internal ADC output to DFSDM channel.
>> + deprecated: true
>>
>> - required:
>> - - io-channels
>> + if:
>> + required:
>> + - st,adc-channels
>> + then:
>> + required:
>> + - io-channels
>> +
>> + patternProperties:
>> + "^channel@([0-9]|1[0-9])$":
>> + required:
>> + - io-backends
>
> Why is this here, rather than with reg above? Only some channels require
> a backend?
The io-backends property is required only when we use st,stm32-dfsdm-adc
compatible. In other words, when we are in an analog use case. In this
case the channel is a consumer of a backend (typically a sd modulator)
In an audio use case (compatible st,stm32-dfsdm-dmic) the backend is not
required.
BRs
Olivier
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