linux-kernel - Re: Enabling pmbus power control

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Message-ID: <20210330180200.GK4976@sirena.org.uk>
Date:   Tue, 30 Mar 2021 19:02:00 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Zev Weiss <zev@...ilderbeest.net>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        Andrew Jeffery <andrew@...id.au>,
        Liam Girdwood <lgirdwood@...il.com>,
        linux-kernel@...r.kernel.org, openbmc@...ts.ozlabs.org
Subject: Re: Enabling pmbus power control

On Tue, Mar 30, 2021 at 12:56:56PM -0500, Zev Weiss wrote:

> Okay, to expand a bit on the description in my initial message -- we've
> got a single chassis with multiple server boards and a single manager board
> that handles, among other things, power control for the servers.
> The manager board has one LM25066 for each attached server, which acts as
> the "power switch" for that server.  There thus really isn't any driver to
> speak of for the downstream device.

This sounds like you need a driver representing those server boards (or
the slots they plug into perhaps) that represents everything about those
boards to userspace, including power switching.  I don't see why you
wouldn't have a driver for that - it's a thing that physically exists
and clearly has some software control, and you'd presumably also expect
to represent some labelling about the slot as well.

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