diff options
Diffstat (limited to 'drivers/pwm')
| -rw-r--r-- | drivers/pwm/pwm-omap-dmtimer.c | 21 |
1 files changed, 7 insertions, 14 deletions
diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c index 85b17b49980b..c56e7256e923 100644 --- a/drivers/pwm/pwm-omap-dmtimer.c +++ b/drivers/pwm/pwm-omap-dmtimer.c @@ -19,6 +19,13 @@ * Limitations: * - When PWM is stopped, timer counter gets stopped immediately. This * doesn't allow the current PWM period to complete and stops abruptly. + * - When PWM is running and changing both duty cycle and period, + * we cannot prevent in software that the output might produce + * a period with mixed settings. Especially when period/duty_cyle + * is updated while the pwm pin is high, current pwm period/duty_cycle + * can get updated as below based on the current timer counter: + * - period for current cycle = current_period + new period + * - duty_cycle for current period = current period + new duty_cycle. */ #include <linux/clk.h> @@ -111,7 +118,6 @@ 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); @@ -187,25 +193,12 @@ 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, load_value); omap->pdata->set_match(omap->dm_timer, true, match_value); dev_dbg(chip->dev, "load value: %#08x (%d), match value: %#08x (%d)\n", load_value, load_value, match_value, match_value); - /* If config was called while timer was running it must be reenabled. */ - if (timer_active) - pwm_omap_dmtimer_start(omap); - mutex_unlock(&omap->mutex); return 0; |