Feedback-ID: i494840e7:Fastmail
Date:   Mon, 13 Mar 2023 14:12:44 +0200
From:   Ido Schimmel <idosch@idosch.org>
To:     Daniel Lezcano <daniel.lezcano@linaro.org>
Cc:     rafael@kernel.org, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, rui.zhang@intel.com,
        Raju Rangoju <rajur@chelsio.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
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        Niklas =?iso-8859-1?Q?S=F6derlund?= 
        <niklas.soderlund@ragnatech.se>,
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        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Alim Akhtar <alim.akhtar@samsung.com>,
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        Eduardo Valentin <edubezval@gmail.com>,
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        "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
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Subject: Re: [PATCH v8 01/29] thermal/core: Add a generic
 thermal_zone_get_trip() function
Message-ID: <ZA8TPDpEVanOpjEp@shredder>
References: <20221003092602.1323944-1-daniel.lezcano@linaro.org>
 <20221003092602.1323944-2-daniel.lezcano@linaro.org>
 <ZA3CFNhU4AbtsP4G@shredder>
 <f78e6b70-a963-c0ca-a4b2-0d4c6aeef1fb@linaro.org>
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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.