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    Subject[PATCH 1/5] thermal/core: Emit a warning if the thermal zone is updated without ops
    Date
    The actual code is silently ignoring a thermal zone update when a
    driver is requesting it without a get_temp ops set.

    That looks not correct, as the caller should not have called this
    function if the thermal zone is unable to read the temperature.

    That makes the code less robust as the check won't detect the driver
    is inconsistently using the thermal API and that does not help to
    improve the framework as these circumvolutions hide the problem at the
    source.

    In order to detect the situation when it happens, let's add a warning
    when the update is requested without the get_temp() ops set.

    Any warning emitted will have to be fixed at the source of the
    problem: the caller must not call thermal_zone_device_update if there
    is not get_temp callback set.

    Cc: Thara Gopinath <thara.gopinath@linaro.org>
    Cc: Amit Kucheria <amitk@kernel.org>
    Cc: linux-pm@vger.kernel.org
    Cc: linux-kernel@vger.kernel.org
    Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
    Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
    ---
    drivers/thermal/thermal_core.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
    index dee40ff41177..e6771e5aeedb 100644
    --- a/drivers/thermal/thermal_core.c
    +++ b/drivers/thermal/thermal_core.c
    @@ -548,7 +548,8 @@ void thermal_zone_device_update(struct thermal_zone_device *tz,
    if (atomic_read(&in_suspend))
    return;

    - if (!tz->ops->get_temp)
    + if (WARN_ONCE(!tz->ops->get_temp, "'%s' must not be called without "
    + "'get_temp' ops set\n", __func__))
    return;

    update_temperature(tz);
    --
    2.17.1
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