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-fsl-ftm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/pwm/pwm-fsl-ftm.c') diff --git a/drivers/pwm/pwm-fsl-ftm.c b/drivers/pwm/pwm-fsl-ftm.c index 3c9738617ceb..59272a920479 100644 --- a/drivers/pwm/pwm-fsl-ftm.c +++ b/drivers/pwm/pwm-fsl-ftm.c @@ -227,7 +227,7 @@ static bool fsl_pwm_is_other_pwm_enabled(struct fsl_pwm_chip *fpc, static int fsl_pwm_apply_config(struct fsl_pwm_chip *fpc, struct pwm_device *pwm, - struct pwm_state *newstate) + const struct pwm_state *newstate) { unsigned int duty; u32 reg_polarity; @@ -298,7 +298,7 @@ static int fsl_pwm_apply_config(struct fsl_pwm_chip *fpc, } static int fsl_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, - struct pwm_state *newstate) + const struct pwm_state *newstate) { struct fsl_pwm_chip *fpc = to_fsl_chip(chip); struct pwm_state *oldstate = &pwm->state; -- cgit v1.2.3-70-g09d2