From 71523d1812aca61e32e742e87ec064e3d8c615e1 Mon Sep 17 00:00:00 2001 From: Uwe Kleine-König Date: Sat, 24 Aug 2019 17:37:07 +0200 Subject: pwm: Ensure pwm_apply_state() doesn't modify the state argument MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It is surprising for a PWM consumer when the variable holding the requested state is modified by pwm_apply_state(). Consider for example a driver doing: #define PERIOD 5000000 #define DUTY_LITTLE 10 ... struct pwm_state state = { .period = PERIOD, .duty_cycle = DUTY_LITTLE, .polarity = PWM_POLARITY_NORMAL, .enabled = true, }; pwm_apply_state(mypwm, &state); ... state.duty_cycle = PERIOD / 2; pwm_apply_state(mypwm, &state); For sure the second call to pwm_apply_state() should still have state.period = PERIOD and not something the hardware driver chose for a reason that doesn't necessarily apply to the second call. So declare the state argument as a pointer to a const type and adapt all drivers' .apply callbacks. Signed-off-by: Uwe Kleine-König Signed-off-by: Thierry Reding --- drivers/pwm/pwm-stm32.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/pwm/pwm-stm32.c') diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c index 740e2dec8313..359b08596d9e 100644 --- a/drivers/pwm/pwm-stm32.c +++ b/drivers/pwm/pwm-stm32.c @@ -440,7 +440,7 @@ static void stm32_pwm_disable(struct stm32_pwm *priv, int ch) } static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, - struct pwm_state *state) + const struct pwm_state *state) { bool enabled; struct stm32_pwm *priv = to_stm32_pwm_dev(chip); @@ -468,7 +468,7 @@ static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, } static int stm32_pwm_apply_locked(struct pwm_chip *chip, struct pwm_device *pwm, - struct pwm_state *state) + const struct pwm_state *state) { struct stm32_pwm *priv = to_stm32_pwm_dev(chip); int ret; -- cgit v1.2.3