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pwm: sifive: Reduce time the controller lock is held

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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@pengutronix.de>
Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Uwe Kleine-König 2022-07-21 12:31:25 +02:00 committed by Thierry Reding
parent 61180f68ad
commit 0f02f491b7
1 changed files with 5 additions and 3 deletions
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8
drivers/pwm/pwm-sifive.c
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@ -41,7 +41,7 @@
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;
@ -76,6 +76,7 @@ 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)
{
@ -144,7 +145,6 @@ 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;
@ -163,14 +163,17 @@ 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_PWMCMP(pwm->hwpwm));
@ -185,7 +188,6 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
exit:
clk_disable(ddata->clk);
mutex_unlock(&ddata->lock);
return ret;
}