linux-kernel - Re: [PATCH 1/2] thermal: tegra-bpmp: Handle offline zones

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Date:   Wed, 8 Feb 2023 17:05:05 +0100
From:   Thierry Reding <thierry.reding@...il.com>
To:     Mikko Perttunen <cyndis@...si.fi>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Srikar Srimath Tirumala <srikars@...dia.com>,
        Mikko Perttunen <mperttunen@...dia.com>,
        Timo Alho <talho@...dia.com>, linux-pm@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] thermal: tegra-bpmp: Handle offline zones

On Wed, Feb 08, 2023 at 05:35:48PM +0200, Mikko Perttunen wrote:
> On 2/8/23 12:31, Thierry Reding wrote:
> > On Tue, Feb 07, 2023 at 03:56:08PM +0200, Mikko Perttunen wrote:
> > > From: Mikko Perttunen <mperttunen@...dia.com>
> > > 
> > > Thermal zones located in power domains may not be accessible when
> > > the domain is powergated. In this situation, reading the temperature
> > > will return -BPMP_EFAULT and the temperature is considered to be
> > > -256C for calculating trips.
> > 
> > Where's that -256C being set? I only see THERMAL_TEMP_INVALID being set
> > as the default for a zone, but that's not -274C, not -256C. If that's
> > the temperature that you're referring to, it might be better to state
> > that we rely on the default temperature rather than any specific number.
> > 
> > Thierry
> 
> It is based on BPMP's internal behavior.

Okay, maybe clarify that part of the sentence then. Could be something
like:

	... will return -BPMP_EFAULT. When evaluating trips, BPMP will
	internally use -256C as the temperature for offline zones.

Thierry

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