From: Milo Kim <milo.kim@ti.com>
To: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: linux-leds@vger.kernel.org, Thierry Reding <thierry.reding@gmail.com>
Subject: Re: leds-pwm: issue in __led_pwm_set()
Date: Sat, 28 Sep 2013 00:51:51 +0900 [thread overview]
Message-ID: <5245A997.1070305@ti.com> (raw)
In-Reply-To: <5243E6CD.4070402@free-electrons.com>
On 09/26/2013 04:48 PM, Alexandre Belloni wrote:
> On 26/09/2013 09:34, Milo Kim wrote:
>>
>> Ah, I didn't mean the pinctrl subsystem. Sorry for confusing you.
>>
>> I just want to know the reason why 'atmel_pwm_disable()' releases the
>> PWM pin.
>> I can't find it in the driver. Am I missing something?
>>
>
> Hum, maybe my wording was wrong. What I meant is that when that
> disabling the PWM channel by using the PWM_DIS
> register, the PWM is not driving the pin anymore. Then, the level goes
> from low (which is correct) to high. Also, the datasheet specifies that
> the pwm has to be enabled to get the correct level when duty == 0 or
> duty == period.
>
> IIRC, this is not the same on TI SoC where duty == 0 don't give you the
> expected behavior and I can understand why there is a pwm_disable()
> there. Maybe we have to have a way to differentiate both cases ?
>
Based on your result, PWM_DIS should be updated when the driver is
unloaded - no PWM consumer anymore.
Why don't you move PWM_DIS register access code from atmel_pwm_disable()
to atmel_pwm_remove()?
If it makes sense, the PWM_EN code also needs to be moved to _probe().
Best regards,
Milo
next prev parent reply other threads:[~2013-09-27 15:51 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-25 20:00 leds-pwm: issue in __led_pwm_set() Alexandre Belloni
2013-09-26 0:28 ` Milo Kim
2013-09-26 7:13 ` Alexandre Belloni
2013-09-26 7:34 ` Milo Kim
2013-09-26 7:48 ` Alexandre Belloni
2013-09-27 15:51 ` Milo Kim [this message]
2013-09-27 16:15 ` Alexandre Belloni
2013-09-27 17:23 ` Milo Kim
2013-09-27 17:33 ` Milo Kim
2013-09-27 18:34 ` Alexandre Belloni
2013-09-27 19:46 ` Alexandre Belloni
2013-09-28 13:29 ` Milo Kim
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