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Message-ID: <e51de5ee-5342-8771-46a3-34d8ee8b9c55@roeck-us.net>
Date: Tue, 25 Jul 2023 07:28:04 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Naresh Solanki <naresh.solanki@...ements.com>,
Rob Herring <robh@...nel.org>
Cc: Jean Delvare <jdelvare@...e.com>,
krzysztof.kozlowski+dt@...aro.org,
Conor Dooley <conor+dt@...nel.org>,
linux-hwmon@...r.kernel.org,
Patrick Rudolph <patrick.rudolph@...ements.com>,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] dt-bindings: hwmon: Add Infineon TDA38640
On 7/25/23 07:17, Naresh Solanki wrote:
> Hi Rob,
>
>
> On Tue, 25 Jul 2023 at 18:40, Rob Herring <robh@...nel.org> wrote:
>>
>> On Tue, Jul 25, 2023 at 01:40:26PM +0200, Naresh Solanki wrote:
>>> From: Patrick Rudolph <patrick.rudolph@...ements.com>
>>>
>>> The TDA38640 has a bug in SVID mode and to enable a workaround
>>> remove the TDA38640 from trivial-devices and add a complete schema.
>>>
>>> The schema adds the custom property 'infineon,en-pin-fixed-level' to
>>> signal a fixed level on the ENABLE pin and to enable the workaround.
>>> When the ENABLE pin is left floating it's internally pulled low.
>>>
>>> If not specified the driver will continue to use the PMBUS_OPERATION
>>> register to enable the regulator. When specified the driver will use
>>> the PMBUS_ON_OFF_CONFIG register to enable the regulator.
>>>
>>> Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
>>> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
>>> ---
>>> .../hwmon/pmbus/infineon,tda38640.yaml | 50 +++++++++++++++++++
>>> .../devicetree/bindings/trivial-devices.yaml | 2 -
>>> 2 files changed, 50 insertions(+), 2 deletions(-)
>>> create mode 100644 Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38640.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38640.yaml b/Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38640.yaml
>>> new file mode 100644
>>> index 000000000000..520112e4e271
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/hwmon/pmbus/infineon,tda38640.yaml
>>> @@ -0,0 +1,50 @@
>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +
>>> +$id: http://devicetree.org/schemas/hwmon/pmbus/infineon,tda38640.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: Infineon TDA38640 Synchronous Buck Regulator with SVID and I2C
>>> +
>>> +description: |
>>> + The Infineon TDA38640 is a 40A Single-voltage Synchronous Buck
>>> + Regulator with SVID and I2C designed for Industrial use.
>>> +
>>> + Datasheet: https://www.infineon.com/dgdl/Infineon-TDA38640-0000-DataSheet-v02_04-EN.pdf?fileId=8ac78c8c80027ecd018042f2337f00c9
>>> +
>>> +properties:
>>> + compatible:
>>> + enum:
>>> + - infineon,tda38640
>>> +
>>> + reg:
>>> + maxItems: 1
>>> +
>>> + infineon,en-pin-fixed-level:
>>> + $ref: /schemas/types.yaml#/definitions/uint32
>>> + description: |
>>> + Fixed level of the ENABLE pin. When specified the PMBUS_ON_OFF_CONFIG
>>> + register is used to enable the regulator instead of the PMBUS_OPERATION
>>> + register to workaround a bug of the tda38640 when operating in SVID-mode.
>>> + If the ENABLE pin is left floating the internal pull-down causes a low
>>> + level on the pin.
>>
>> Neither this nor the commit message answers how do I decide if I set
>> this property or not? How you work-around it is not that relevant to the
>> binding.
> Sure will update this as:
> The property becomes relevant when dealing with the tda38640 in
> SVID-mode, providing an alternative method to enable the regulator by
> using the PMBUS_ON_OFF_CONFIG register instead of the PMBUS_OPERATION
> register
>
As mentioned in the other e-mail, I'll want to see an explanation why
this property is even needed. The series claims that the chip has a bug
in SVID mode. It is kind of unusual that we would enable a workaround
for a bug with a devicetree property if the circumstance (SVID mode)
can be determined automatically.
Guenter
> Regards,
> Naresh
>>
>>> +
>>> +required:
>>> + - compatible
>>> + - reg
>>> +
>>> +additionalProperties: false
>>> +
>>> +examples:
>>> + - |
>>> + i2c {
>>> + #address-cells = <1>;
>>> + #size-cells = <0>;
>>> +
>>> + tda38640@40 {
>>> + compatible = "infineon,tda38640";
>>> + reg = <0x40>;
>>> + };
>>> + };
>>> +
>>> diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml
>>> index 6e24c4d25ec3..2b1fbb2a672b 100644
>>> --- a/Documentation/devicetree/bindings/trivial-devices.yaml
>>> +++ b/Documentation/devicetree/bindings/trivial-devices.yaml
>>> @@ -151,8 +151,6 @@ 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
>>>
>>> base-commit: 55612007f16b5d7b1fb83a7b0f5bb686829db7c7
>>> --
>>> 2.41.0
>>>
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