linux-kernel - Re: [PATCH v4] PWM: atmel-pwm: add PWM controller driver

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Message-ID: <5247FABD.9070405@atmel.com>
Date:	Sun, 29 Sep 2013 18:02:37 +0800
From:	Bo Shen <voice.shen@...el.com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
CC:	Thierry Reding <thierry.reding@...il.com>,
	<devicetree@...r.kernel.org>, <linux-pwm@...r.kernel.org>,
	<nicolas.ferre@...el.com>, <linux-kernel@...r.kernel.org>,
	<plagnioj@...osoft.com>, <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4] PWM: atmel-pwm: add PWM controller driver

Hi Alexandre,

On 9/28/2013 00:52, Alexandre Belloni wrote:
[snip]

>> +static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +	int ret;
>> +
>> +	ret = clk_enable(atmel_pwm->clk);
>> +	if (ret) {
>> +		pr_err("failed to enable pwm clock\n");
>> +		return ret;
>> +	}
>> +
>
> This will increment clk->enable_count each time it is called.

Yes, that's true.

>> +	atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
>> +
>> +	return 0;
>> +}
>> +
>> +static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +	u32 val;
>> +
>> +	atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
>> +
>> +	val = atmel_pwm_readl(atmel_pwm, PWM_SR);
>> +	if ((val & PWM_SR_ALL_CH_ON) == 0)
>> +		clk_disable(atmel_pwm->clk);
>> +}
>
> This will decrement clk->enable_count only once there are no pwm enabled
> anymore.  So in you enable more than one channel, you will never disable
> the clock. The simple fix is to always call clk_diasble, regardless of
> the state of the other channels.

Thank for point out this.

I see you have sent out a patch to fix it (however the other contents of 
your patch doesn't work). So, do you prefer I send out v5 patch to fix 
this? or you fix your patch at same time fix this issue?

Best Regards,
Bo Shen
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