hi Sjoerd, Are you referring to handle of polarity (PWM_POLARITY_NORMAL/PWM_POLARITY_INVERSED) during enable and disable. How can I analyses if the clock is high and low. -Anand Moon On 15 April 2015 at 14:04, Sjoerd Simons <sjoerd.simons@xxxxxxxxxxxxxxx> wrote: > 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 <sjoerd.simons@xxxxxxxxxxxxxxx> > Collabora Ltd. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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