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    Subject[PATCH 5.15 088/171] hwmon: (pwm-fan) Ensure the fan going on in .probe()
    Date
    From: Billy Tsai <billy_tsai@aspeedtech.com>

    commit a2ca752055edd39be38b887e264d3de7ca2bc1bb upstream.

    Before commit 86585c61972f ("hwmon: (pwm-fan) stop using legacy
    PWM functions and some cleanups") pwm_apply_state() was called
    unconditionally in pwm_fan_probe(). In this commit this direct
    call was replaced by a call to __set_pwm(ct, MAX_PWM) which
    however is a noop if ctx->pwm_value already matches the value to
    set.
    After probe the fan is supposed to run at full speed, and the
    internal driver state suggests it does, but this isn't asserted
    and depending on bootloader and pwm low-level driver, the fan
    might just be off.
    So drop setting pwm_value to MAX_PWM to ensure the check in
    __set_pwm doesn't make it exit early and the fan goes on as
    intended.

    Cc: stable@vger.kernel.org
    Fixes: 86585c61972f ("hwmon: (pwm-fan) stop using legacy PWM functions and some cleanups")
    Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
    Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
    Link: https://lore.kernel.org/r/20211130092212.17783-1-billy_tsai@aspeedtech.com
    Signed-off-by: Guenter Roeck <linux@roeck-us.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/hwmon/pwm-fan.c | 2 --
    1 file changed, 2 deletions(-)

    --- a/drivers/hwmon/pwm-fan.c
    +++ b/drivers/hwmon/pwm-fan.c
    @@ -336,8 +336,6 @@ static int pwm_fan_probe(struct platform
    return ret;
    }

    - ctx->pwm_value = MAX_PWM;
    -
    pwm_init_state(ctx->pwm, &ctx->pwm_state);

    /*

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