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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 /include/linux/pwm.h
parentc9675829ba4b0e95c613f6d6d83d2b5cb9c5371c (diff)
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 'include/linux/pwm.h')
-rw-r--r--include/linux/pwm.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 24632a7a7d11..b2c9c460947d 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -262,7 +262,7 @@ struct pwm_ops {
int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_capture *result, unsigned long timeout);
int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
- struct pwm_state *state);
+ const struct pwm_state *state);
void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state);
struct module *owner;
@@ -316,7 +316,7 @@ struct pwm_capture {
/* PWM user APIs */
struct pwm_device *pwm_request(int pwm_id, const char *label);
void pwm_free(struct pwm_device *pwm);
-int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state);
+int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state);
int pwm_adjust_config(struct pwm_device *pwm);
/**