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From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Tue, 9 Jan 2024 14:42:52 +0100
Message-ID: <CAJZ5v0gE6eEpALrfxHvCd5TRqjB+v8pffG4CKLTVXiSvuiWhHg@mail.gmail.com>
Subject: Re: [PATCH] thermal/sysfs: Always enable hysteresis write support
To: Manaf Meethalavalappu Pallikunhi <quic_manafm@quicinc.com>
Cc: "Rafael J . Wysocki" <rafael@kernel.org>, Daniel Lezcano <daniel.lezcano@linaro.org>, 
	Zhang Rui <rui.zhang@intel.com>, Lukasz Luba <lukasz.luba@arm.com>, linux-pm@vger.kernel.org, 
	linux-kernel@vger.kernel.org
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On Sat, Jan 6, 2024 at 8:16=E2=80=AFPM Manaf Meethalavalappu Pallikunhi
<quic_manafm@quicinc.com> wrote:
>
> The commit 2e38a2a981b2("thermal/core: Add a generic
> thermal_zone_set_trip() function") adds the support to update
> trip hysteresis even if set_trip_hyst() operation is not defined.
> But during hysteresis attribute creation, if this operation is
> defined then only it enables hysteresis write access. It leads
> to a case where hysteresis sysfs will be read only for a thermal
> zone when its set_trip_hyst() operation is not defined.

Which is by design.

For some thermal zone types (eg. acpi), updating trip hysteresis via
sysfs might lead to incorrect behavior.