netdev - Re: [PATCH v8 01/29] thermal/core: Add a generic thermal_zone_get

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Message-ID: <ZA8TPDpEVanOpjEp@shredder>
Date:   Mon, 13 Mar 2023 14:12:44 +0200
From:   Ido Schimmel <idosch@...sch.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     rafael@...nel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, rui.zhang@...el.com,
        Raju Rangoju <rajur@...lsio.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
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        Miquel Raynal <miquel.raynal@...tlin.com>,
        Amit Kucheria <amitk@...nel.org>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Broadcom Kernel Team <bcm-kernel-feedback-list@...adcom.com>,
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        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
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        Niklas Söderlund 
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        Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Antoine Tenart <atenart@...nel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Dmitry Osipenko <digetx@...il.com>, netdev@...r.kernel.org,
        platform-driver-x86@...r.kernel.org,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-omap@...r.kernel.org,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        danieller@...dia.com, vadimp@...dia.com, petrm@...dia.com
Subject: Re: [PATCH v8 01/29] thermal/core: Add a generic
 thermal_zone_get_trip() function

On Mon, Mar 13, 2023 at 11:45:41AM +0100, Daniel Lezcano wrote:
> Thanks for reporting this, I think the fix you are proposing is correct
> regarding the previous behavior.
> 
> However, I disagree with the commit 81ad4276b505, because it defines the
> zero as an invalid trip point. But some platforms have warming devices, when
> the temperature is too cold, eg 0°C, we enable the warming device in order
> to stay in the functioning temperature range.
> 
> Other devices can do the same with negative temperature values.
> 
> This feature is not yet upstream and the rework of the trip point should
> allow proper handling of cold trip points.
> 
> If you can send the change to fix the regression that would be great.

Thanks for the reply. Will send you the fix later this week. I want to
test it across all of our systems.

> 
> But keep in mind, the driver is assuming an internal thermal framework
> behavior. The trips_disabled is only to overcome a trip point description
> bug and you should not rely on it as well as not changing the trip points on
> the fly after they are registered.
> 
> Actually, the mlxsw driver should just build a valid array of trip points
> without 0°C trip point and pass it to
> thermal_zone_device_register_with_trips(). That would be a proper change
> without relying on a side effect of the thermal trip bug 0°C workaround.

Understood. Will check with Vadim what we can do in order not to rely on
this behavior.