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    Subject[PATCH 4.9 55/95] pwm: rcar: Fix a condition to prevent mismatch value setting to duty
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Ryo Kodama <ryo.kodama.vz@renesas.com>

    commit 6225f9c64b40bc8a22503e9cda70f55d7a9dd3c6 upstream.

    This patch fixes an issue that is possible to set mismatch value to duty
    for R-Car PWM if we input the following commands:

    # cd /sys/class/pwm/<pwmchip>/
    # echo 0 > export
    # cd pwm0
    # echo 30 > period
    # echo 30 > duty_cycle
    # echo 0 > duty_cycle
    # cat duty_cycle
    0
    # echo 1 > enable
    --> Then, the actual duty_cycle is 30, not 0.

    So, this patch adds a condition into rcar_pwm_config() to fix this
    issue.

    Signed-off-by: Ryo Kodama <ryo.kodama.vz@renesas.com>
    [shimoda: revise the commit log and add Fixes and Cc tags]
    Fixes: ed6c1476bf7f ("pwm: Add support for R-Car PWM Timer")
    Cc: Cc: <stable@vger.kernel.org> # v4.4+
    Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
    Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/pwm/pwm-rcar.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    --- a/drivers/pwm/pwm-rcar.c
    +++ b/drivers/pwm/pwm-rcar.c
    @@ -156,8 +156,12 @@ static int rcar_pwm_config(struct pwm_ch
    if (div < 0)
    return div;

    - /* Let the core driver set pwm->period if disabled and duty_ns == 0 */
    - if (!pwm_is_enabled(pwm) && !duty_ns)
    + /*
    + * Let the core driver set pwm->period if disabled and duty_ns == 0.
    + * But, this driver should prevent to set the new duty_ns if current
    + * duty_cycle is not set
    + */
    + if (!pwm_is_enabled(pwm) && !duty_ns && !pwm->state.duty_cycle)
    return 0;

    rcar_pwm_update(rp, RCAR_PWMCR_SYNC, RCAR_PWMCR_SYNC, RCAR_PWMCR);

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