linux-kernel - Re: [PATCH v2 1/2] dt-bindings: trivial-devices: add ltp8800

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Message-ID: <2bdc5b60-2442-4291-a2f2-2e3802b7e982@roeck-us.net>
Date: Wed, 6 Nov 2024 08:35:33 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Conor Dooley <conor@...nel.org>
Cc: Cedric Encarnacion <cedricjustine.encarnacion@...log.com>,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-i2c@...r.kernel.org, linux-doc@...r.kernel.org,
 linux-hwmon@...r.kernel.org, Jean Delvare <jdelvare@...e.com>,
 Jonathan Corbet <corbet@....net>,
 Delphine CC Chiu <Delphine_CC_Chiu@...ynn.com>, Rob Herring
 <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Peter Yin <peteryin.openbmc@...il.com>,
 Noah Wang <noahwang.wang@...look.com>, Marek Vasut <marex@...x.de>,
 Lukas Wunner <lukas@...ner.de>
Subject: Re: [PATCH v2 1/2] dt-bindings: trivial-devices: add ltp8800

On 11/6/24 08:06, Conor Dooley wrote:
> On Tue, Nov 05, 2024 at 08:34:01PM -0800, Guenter Roeck wrote:
>> On 11/5/24 19:09, Cedric Encarnacion wrote:
>>> Add Analog Devices LTP8800-1A, LTP8800-2, and LTP8800-4A DC/DC μModule
>>> regulator.
> 
> A single compatible for 3 devices is highly suspect. What is
> different between these devices?
> 

The maximum supported current is different.

-2:  135A
-1A: 150A
-4A: 200A

Programming is exactly the same, which is why I had asked the submitter to use
a single compatible property. Sorry for that if it is inappropriate.

Is there some guidance explaining when to use a single vs. multiple compatible
properties for different chip variants ?

Note that there are also LTP8803-1A which supports 160A, and LTP8802A-1B
which supports 140A. Maybe there are more, but those are the ones I can find in
public. I don't know if there is a difference from programming perspective compared
to the LTP8800 chip variants; the datasheets are too vague to be sure. It would be
useful to know if those chips should get separate compatible entries if programming
is the same.

Thanks,
Guenter