Hello, On Mon, Feb 24, 2020 at 10:51:34AM +0530, Lokesh Vutla wrote: > Only the Timer control register(TCLR) can be updated only when the timer > is stopped. Registers like Counter register(TCRR), loader register(TLDR), > match register(TMAR) can be updated when the counter is running. Since > TCLR is not updated in pwm_omap_dmtimer_config(), do not stop the > timer for period/duty_cycle update. > > Signed-off-by: Lokesh Vutla <lokeshvutla@xxxxxx> > --- > drivers/pwm/pwm-omap-dmtimer.c | 14 -------------- > 1 file changed, 14 deletions(-) > > diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c > index f13be7216847..58c61559e72f 100644 > --- a/drivers/pwm/pwm-omap-dmtimer.c > +++ b/drivers/pwm/pwm-omap-dmtimer.c > @@ -102,7 +102,6 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, > u32 load_value, match_value; > struct clk *fclk; > unsigned long clk_rate; > - bool timer_active; > > dev_dbg(chip->dev, "requested duty cycle: %d ns, period: %d ns\n", > duty_ns, period_ns); > @@ -178,25 +177,12 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, > load_value = (DM_TIMER_MAX - period_cycles) + 1; > match_value = load_value + duty_cycles - 1; > > - /* > - * We MUST stop the associated dual-mode timer before attempting to > - * write its registers, but calls to omap_dm_timer_start/stop must > - * be balanced so check if timer is active before calling timer_stop. > - */ > - timer_active = pm_runtime_active(&omap->dm_timer_pdev->dev); > - if (timer_active) > - omap->pdata->stop(omap->dm_timer); > - > omap->pdata->set_load(omap->dm_timer, true, load_value); > omap->pdata->set_match(omap->dm_timer, true, match_value); (Without having looked into the depths of the driver I assume .set_load() sets the period of the PWM and .set_match() the duty cycle.) What happens on a running PWM if you change the period? Consider you change from duty_cycle = 1000, period = 5000 to duty_cycle = 4000, period = 10000. As you set the period first, can it happen the hardware produces a cycle with duty_cycle = 1000, period = 10000? Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
