summaryrefslogtreecommitdiff
path: root/drivers/pwm/pwm-sun4i.c
diff options
context:
space:
mode:
authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2019-08-24 18:37:07 +0300
committerThierry Reding <thierry.reding@gmail.com>2019-09-21 04:25:10 +0300
commit71523d1812aca61e32e742e87ec064e3d8c615e1 (patch)
tree20491f0323c9b71d0628741824c4dcf992e22363 /drivers/pwm/pwm-sun4i.c
parentc9675829ba4b0e95c613f6d6d83d2b5cb9c5371c (diff)
downloadlinux-71523d1812aca61e32e742e87ec064e3d8c615e1.tar.xz
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-sun4i.c')
-rw-r--r--drivers/pwm/pwm-sun4i.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 39007a7c0d83..6f5840a1a82d 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -145,7 +145,7 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip,
}
static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm,
- struct pwm_state *state,
+ const struct pwm_state *state,
u32 *dty, u32 *prd, unsigned int *prsclr)
{
u64 clk_rate, div = 0;
@@ -196,7 +196,7 @@ static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm,
}
static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
- struct pwm_state *state)
+ const struct pwm_state *state)
{
struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
struct pwm_state cstate;