2020-02-24 05:23:02

by Lokesh Vutla

Subject: [PATCH 2/4] pwm: omap-dmtimer: Fix pwm enabling sequence

To configure DM timer is pwm mode the following needs to be set in
OMAP_TIMER_CTRL_REG using set_pwm callback:
- Set toggle mode on PORTIMERPWM output pin
- Set trigger on overflow and match on PORTIMERPWM output pin.
- Set auto reload

This is a one time configuration and needs to be set before the start of
the dm timer. But the current driver tries to set the same configuration
for every period/duty cycle update, which is not needed. So move the pwm
setup before enabling timer and do not update it in pwm_omap_dmtimer_config.

Signed-off-by: Lokesh Vutla <[email protected]>
---
drivers/pwm/pwm-omap-dmtimer.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c
index 2e35bf9a7936..f13be7216847 100644
--- a/drivers/pwm/pwm-omap-dmtimer.c
+++ b/drivers/pwm/pwm-omap-dmtimer.c
@@ -73,6 +73,10 @@ static int pwm_omap_dmtimer_enable(struct pwm_chip *chip,
struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);

mutex_lock(&omap->mutex);
+ omap->pdata->set_pwm(omap->dm_timer,
+ pwm_get_polarity(pwm) == PWM_POLARITY_INVERSED,
+ true, OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE);
+
pwm_omap_dmtimer_start(omap);
mutex_unlock(&omap->mutex);

@@ -189,10 +193,6 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip,
dev_dbg(chip->dev, "load value: %#08x (%d), match value: %#08x (%d)\n",
load_value, load_value, match_value, match_value);

- omap->pdata->set_pwm(omap->dm_timer,
- pwm_get_polarity(pwm) == PWM_POLARITY_INVERSED,
- true, OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE);
-
/* If config was called while timer was running it must be reenabled. */
if (timer_active)
pwm_omap_dmtimer_start(omap);
--
2.23.0

2020-02-24 08:50:26

by Uwe Kleine-König

Subject: Re: [PATCH 2/4] pwm: omap-dmtimer: Fix pwm enabling sequence

On Mon, Feb 24, 2020 at 10:51:33AM +0530, Lokesh Vutla wrote:
> To configure DM timer is pwm mode the following needs to be set in
> OMAP_TIMER_CTRL_REG using set_pwm callback:
> - Set toggle mode on PORTIMERPWM output pin
> - Set trigger on overflow and match on PORTIMERPWM output pin.
> - Set auto reload
>
> This is a one time configuration and needs to be set before the start of
> the dm timer. But the current driver tries to set the same configuration
> for every period/duty cycle update, which is not needed. So move the pwm
> setup before enabling timer and do not update it in pwm_omap_dmtimer_config.

Is this change kind of moot with the conversion to .apply in the next
patch?

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | https://www.pengutronix.de/ |

2020-02-25 05:03:53

by Lokesh Vutla

Subject: Re: [PATCH 2/4] pwm: omap-dmtimer: Fix pwm enabling sequence

Hi Uwe,

On 24/02/20 2:19 PM, Uwe Kleine-König wrote:
> On Mon, Feb 24, 2020 at 10:51:33AM +0530, Lokesh Vutla wrote:
>> To configure DM timer is pwm mode the following needs to be set in
>> OMAP_TIMER_CTRL_REG using set_pwm callback:
>> - Set toggle mode on PORTIMERPWM output pin
>> - Set trigger on overflow and match on PORTIMERPWM output pin.
>> - Set auto reload
>>
>> This is a one time configuration and needs to be set before the start of
>> the dm timer. But the current driver tries to set the same configuration
>> for every period/duty cycle update, which is not needed. So move the pwm
>> setup before enabling timer and do not update it in pwm_omap_dmtimer_config.
>
> Is this change kind of moot with the conversion to .apply in the next
> patch?

Yes, but I didn't want to club it with the conversion to .apply as this is
functional change wrt to the existing driver.

Thanks and regards,
Lokesh