Re: [PATCH v2 2/2] hwmon: pmbus: add driver for ltp8800-1a, ltp8800-4a, and ltp8800-2

Guenter Roeck
2024-11-08T14:31:16Z

On 11/7/24 23:44, Encarnacion, Cedric justine wrote:
>> -----Original Message-----
>> From: Guenter Roeck <groeck7@gmail.com> On Behalf Of Guenter Roeck
>> Sent: Thursday, November 7, 2024 9:45 AM
>> To: Encarnacion, Cedric justine <Cedricjustine.Encarnacion@analog.com>;
>> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
>> i2c@vger.kernel.org; linux-doc@vger.kernel.org; linux-
>> hwmon@vger.kernel.org
>> Cc: Jean Delvare <jdelvare@suse.com>; Jonathan Corbet <corbet@lwn.net>;
>> Delphine CC Chiu <Delphine_CC_Chiu@Wiwynn.com>; Rob Herring
>> <robh@kernel.org>; Krzysztof Kozlowski <krzk+dt@kernel.org>; Conor Dooley
>> <conor+dt@kernel.org>; Peter Yin <peteryin.openbmc@gmail.com>; Noah
>> Wang <noahwang.wang@outlook.com>; Marek Vasut <marex@denx.de>;
>> Lukas Wunner <lukas@wunner.de>
>> Subject: Re: [PATCH v2 2/2] hwmon: pmbus: add driver for ltp8800-1a,
>> ltp8800-4a, and ltp8800-2
>>
>> [External]
>>
>> On 11/5/24 19:09, Cedric Encarnacion wrote:
>>> LTP8800-1A 54V, 150A DC/DC µModule Regulator with PMBus Interface
>>> LTP8800-4A 54V, 200A DC/DC µModule Regulator with PMBus Interface
>>> LTP8800-2 54V, 135A DC/DC μModule Regulator with PMBus Interface
>>>
>>> The LTP8800 is a family of step-down μModule regulators that provides
>>> microprocessor core voltage from 54V power distribution architecture. It
>>> features telemetry monitoring of input/output voltage, input current,
>>> output power, and temperature over PMBus.
>>>
>>> Signed-off-by: Cedric Encarnacion <cedricjustine.encarnacion@analog.com>
>>
>> Looking closer into the datasheets, I found that the PMBus commands are
>> identical
>> to those of ADP1055, and an extension of the ADP1050 driver to support
>> ADP1055
>> has been submitted.
>>
>> With this in mind, please explain why this series warrants a new driver instead
>> of just extending the existing driver to support LTP8800.
>
> It also appears that the LTP8800-1A regulator makes use of
> factory-programmed ADP1055 but this is not explicitly stated for other
> variants. Initially, I thought a new client driver would be reasonable
> since this device is intended as a regulator while ADP1050/ADP1055 is a
> more customizable digital controller, and both have their own multiple

We use the same driver for many variants of ltc2978. We should do the same here.

> variants. Indeed, it may be more reasonable to extend existing driver since
> they are exposing the same feature. In this case, can this be done in
> succeeding version/s of this series?
>

Succeeding version, but please synchronize with the engineer adding support
for adp1055 to the adp1050 driver. Another option would be to make adding support
for adp1051/adp1055 and adding support for ltp880X chips a patch series. The
introductory patch could then reference the original patch series.

Thanks,
Guenter