linux-kernel - Re: [PATCH v2] thermal: core: Add trip thresholds for trip crossing detection

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Date:   Fri, 03 Nov 2023 13:43:33 -0400
From:   srinivas pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Lukasz Luba <lukasz.luba@....com>
Subject: Re: [PATCH v2] thermal: core: Add trip thresholds for trip crossing
 detection

On Fri, 2023-11-03 at 17:30 +0100, Daniel Lezcano wrote:
> On 03/11/2023 16:42, srinivas pandruvada wrote:
> > On Fri, 2023-11-03 at 15:56 +0100, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > > 
> > > The trip crossing detection in handle_thermal_trip() does not
> > > work
> > > correctly in the cases when a trip point is crossed on the way up
> > > and
> > > then the zone temperature stays above its low temperature (that
> > > is,
> > > its
> > > temperature decreased by its hysteresis).  The trip temperature
> > > may
> > > be passed by the zone temperature subsequently in that case, even
> > > multiple times, but that does not count as the trip crossing as
> > > long
> > > as
> > > the zone temperature does not fall below the trip's low
> > > temperature
> > > or,
> > > in other words, until the trip is crossed on the way down.
> > 
> > In other words you want to avoid multiple trip UP notifications
> > without
> > a corresponding DOWN notification.
> > 
> > This will reduce unnecessary noise to user space. Is this the
> > intention?
> 
> Not only reduce noise but give a correct information. Otherwise the 
> userspace will have to figure out if there are duplicate events after
> the first event happened. The same happen (less often) when crossing
> the 
> trip point the way down.
Correct.
The patch looks good to me.

Thanks,
Srinivas


> 
> 
>