On Wed, 2015-04-15 at 03:35 +0930, Anand Moon wrote: > diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c > index 3e9b583..b579753 100644 > --- a/drivers/pwm/pwm-samsung.c > +++ b/drivers/pwm/pwm-samsung.c > @@ -247,6 +247,7 @@ static int pwm_samsung_enable(struct pwm_chip *chip, > struct pwm_device *pwm) > tcon &= ~TCON_MANUALUPDATE(tcon_chan); > tcon |= TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan); > writel(tcon, our_chip->base + REG_TCON); > + clk_prepare_enable(our_chip->base_clk); > > spin_unlock_irqrestore(&samsung_pwm_lock, flags); > > @@ -265,6 +266,7 @@ static void pwm_samsung_disable(struct pwm_chip *chip, > struct pwm_device *pwm) > tcon = readl(our_chip->base + REG_TCON); > tcon &= ~TCON_AUTORELOAD(tcon_chan); > writel(tcon, our_chip->base + REG_TCON); > + clk_disable_unprepare(our_chip->base_clk); > > spin_unlock_irqrestore(&samsung_pwm_lock, flags); > }
As far as i can tell this code doesn't have any effect. clk_enable is refcounted, so the clock will stay enabled for as long as the driver is loaded (as it's enabled in _probe). Your code above just raises and lowers the clocks enabled refcount, but won't actually ever cause it to be disabled. With respect to trying to disabling the clocks on pwm_disable, that will need some more work to ensure the output signal has the expected level when you turn of the clock. Specifically, when disabling from a non-100% duty state the driver relies on the PWM turning the output signal low at the end of a duty cycle. However if you turn off the clock at the start of a duty cycle while the output signal is still high it will unexpectedly remain high. -- Sjoerd Simons <[email protected]> Collabora Ltd. -- To unsubscribe from this list: send the line "unsubscribe linux-pwm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
