linux-kernel - Re: [PATCH] hwmon: (pmbus/tda38640) Add driver for Infineon TDA38640 Voltage Regulator

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Date:   Tue, 24 Jan 2023 17:49:18 +0530
From:   Naresh Solanki <naresh.solanki@...ements.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Jean Delvare <jdelvare@...e.com>
Cc:     linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        Rob Herring <robh@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (pmbus/tda38640) Add driver for Infineon TDA38640
 Voltage Regulator

Hi

On 24-01-2023 05:35 pm, Krzysztof Kozlowski wrote:
> On 24/01/2023 12:45, Naresh Solanki wrote:
>> Hi
>>
>> On 24-01-2023 04:40 pm, Krzysztof Kozlowski wrote:
>>> On 24/01/2023 12:01, Naresh Solanki wrote:
>>>> From: Patrick Rudolph <patrick.rudolph@...ements.com>
>>>>
>>>> Add the pmbus driver for the Infineon TDA38640 voltage regulator.
>>>>
>>>> Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
>>>> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
>>>> ---
>>>>    .../devicetree/bindings/trivial-devices.yaml  |  2 +
>>>
>>> Split bindings from driver code.
>> Sure
>>>
>>>>    drivers/hwmon/pmbus/Kconfig                   | 16 ++++
>>>>    drivers/hwmon/pmbus/Makefile                  |  1 +
>>>>    drivers/hwmon/pmbus/tda38640.c                | 78 +++++++++++++++++++
>>>>    4 files changed, 97 insertions(+)
>>>>    create mode 100644 drivers/hwmon/pmbus/tda38640.c
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml
>>>> index f5c0a6283e61..a28b02036489 100644
>>>> --- a/Documentation/devicetree/bindings/trivial-devices.yaml
>>>> +++ b/Documentation/devicetree/bindings/trivial-devices.yaml
>>>> @@ -141,6 +141,8 @@ properties:
>>>>              - infineon,slb9645tt
>>>>                # Infineon SLB9673 I2C TPM 2.0
>>>>              - infineon,slb9673
>>>> +            # Infineon TDA38640 Voltage Regulator
>>>> +          - infineon,tda38640
>>>>                # Infineon TLV493D-A1B6 I2C 3D Magnetic Sensor
>>>>              - infineon,tlv493d-a1b6
>>>>                # Infineon Multi-phase Digital VR Controller xdpe11280
>>>> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
>>>> index 30448e049486..9f4bbb9c487a 100644
>>>> --- a/drivers/hwmon/pmbus/Kconfig
>>>> +++ b/drivers/hwmon/pmbus/Kconfig
>>>> @@ -395,6 +395,22 @@ config SENSORS_STPDDC60
>>>>    	  This driver can also be built as a module. If so, the module will
>>>>    	  be called stpddc60.
>>>>    
>>>> +config SENSORS_TDA38640
>>>> +	tristate "Infineon TDA38640"
>>>> +	help
>>>> +	  If you say yes here you get hardware monitoring support for Infineon
>>>> +	  TDA38640.
>>>> +
>>>> +	  This driver can also be built as a module. If so, the module will
>>>> +	  be called tda38640.
>>>> +
>>>> +config SENSORS_TDA38640_REGULATOR
>>>> +	bool "Regulator support for TDA38640 and compatibles"
>>>> +	depends on SENSORS_TDA38640 && REGULATOR
>>>> +	help
>>>> +	  If you say yes here you get regulator support for Infineon
>>>> +	  TDA38640 as regulator.
>>>
>>> Drop entire option, why is it needed?
>> You mean regulator option ?
>> This is how other pmbus regulator devices have provided option.
> 
> Hmmm... I wonder why this is of any use.
 From what I can think of. Chip also provide pin to control regulator 
enable. If that is used in the design then the regulator option may not 
be needed.
> 
>>>
>>>> +
>>>>    config SENSORS_TPS40422
>>>>    	tristate "TI TPS40422"
>>>>    	help
> 
> (...)
Yes this doesn't has regulator support in driver.
> 
>>>
>>>> +static const struct of_device_id tda38640_of_match[] = {
>>>> +	{ .compatible = "infineon,tda38640"},
>>>> +	{ },
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, tda38640_of_match);
>>>
>>> Where is it used? You miss the user.
>> I'm not sure if I get your question right.
>> This chip is used in sbp1 board to power CPU rails.
> 
> No, where is the data structure used (except module autoloading)?
My use case is loading the driver base on DT. Not sure of other uses.
> 
> Best regards,
> Krzysztof
> 
Best Regards,
Naresh