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authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2019-08-24 17:37:07 +0200
committerThierry Reding <thierry.reding@gmail.com>2019-09-21 03:25:10 +0200
commit71523d1812aca61e32e742e87ec064e3d8c615e1 (patch)
tree20491f0323c9b71d0628741824c4dcf992e22363 /drivers/pwm/pwm-meson.c
parentpwm: fsl-ftm: Don't update the state for the caller of pwm_apply_state() (diff)
downloadlinux-71523d1812aca61e32e742e87ec064e3d8c615e1.tar.xz
linux-71523d1812aca61e32e742e87ec064e3d8c615e1.zip
pwm: Ensure pwm_apply_state() doesn't modify the state argument
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 <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm/pwm-meson.c')
-rw-r--r--drivers/pwm/pwm-meson.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
index 3cbff5cbb789..6245bbdb6e6c 100644
--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -159,7 +159,7 @@ static void meson_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
}
static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm,
- struct pwm_state *state)
+ const struct pwm_state *state)
{
struct meson_pwm_channel *channel = pwm_get_chip_data(pwm);
unsigned int duty, period, pre_div, cnt, duty_cnt;
@@ -265,7 +265,7 @@ static void meson_pwm_disable(struct meson_pwm *meson, struct pwm_device *pwm)
}
static int meson_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
- struct pwm_state *state)
+ const struct pwm_state *state)
{
struct meson_pwm_channel *channel = pwm_get_chip_data(pwm);
struct meson_pwm *meson = to_meson_pwm(chip);