linux-kernel - Re: Enabling pmbus power control

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Date:   Tue, 30 Mar 2021 12:38:10 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Mark Brown <broonie@...nel.org>
Cc:     Zev Weiss <zev@...ilderbeest.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 07:02:00PM +0100, Mark Brown wrote:
> 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.

Absolutely agree.

Thanks,
Guenter