From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
[ Upstream commit 0f02f491b786143f08eb19840f1cf4f12aec6dee ]
The lock is only to serialize access and update to user_count and
approx_period between different PWMs served by the same pwm_chip.
So the lock needs only to be taken during the check if the (chip global)
period can and/or needs to be changed.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Tested-by: Emil Renner Berthing <emil.renner.berthing@xxxxxxxxxxxxx>
Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx>
Stable-dep-of: 334c7b13d383 ("pwm: sifive: Always let the first pwm_apply_state succeed")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/pwm/pwm-sifive.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index 538297ef82558..980ddcdd52953 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -43,7 +43,7 @@
struct pwm_sifive_ddata {
struct pwm_chip chip;
- struct mutex lock; /* lock to protect user_count */
+ struct mutex lock; /* lock to protect user_count and approx_period */
struct notifier_block notifier;
struct clk *clk;
void __iomem *regs;
@@ -78,6 +78,7 @@ static void pwm_sifive_free(struct pwm_chip *chip, struct pwm_device *pwm)
mutex_unlock(&ddata->lock);
}
+/* Called holding ddata->lock */
static void pwm_sifive_update_clock(struct pwm_sifive_ddata *ddata,
unsigned long rate)
{
@@ -166,7 +167,6 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
return ret;
}
- mutex_lock(&ddata->lock);
cur_state = pwm->state;
enabled = cur_state.enabled;
@@ -185,14 +185,17 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
/* The hardware cannot generate a 100% duty cycle */
frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
+ mutex_lock(&ddata->lock);
if (state->period != ddata->approx_period) {
if (ddata->user_count != 1) {
+ mutex_unlock(&ddata->lock);
ret = -EBUSY;
goto exit;
}
ddata->approx_period = state->period;
pwm_sifive_update_clock(ddata, clk_get_rate(ddata->clk));
}
+ mutex_unlock(&ddata->lock);
writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP0 +
pwm->hwpwm * PWM_SIFIVE_SIZE_PWMCMP);
@@ -202,7 +205,6 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
exit:
clk_disable(ddata->clk);
- mutex_unlock(&ddata->lock);
return ret;
}
--
2.39.2
