From mboxrd@z Thu Jan  1 00:00:00 1970
From: jy0922.shim@samsung.com (Joonyoung Shim)
Date: Thu, 03 Nov 2011 11:24:24 +0900
Subject: [PATCH] ARM: SAMSUNG: Add clk enable/disable of pwm
In-Reply-To: <012701cc99cc$300dca50$90295ef0$%kim@samsung.com>
References: <1319505701-9784-1-git-send-email-jy0922.shim@samsung.com>
	<012701cc99cc$300dca50$90295ef0$%kim@samsung.com>
Message-ID: <4EB1FB58.9050503@samsung.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

11/03/2011 10:59 AM, Kukjin Kim ? ?:
> Joonyoung Shim wrote:
>> PWM timers use pclk("timers" clk) as parent clk. If this pclk is the
>> disabled state when PWM driver is probed, then it causes wrong read and
>> write operation about registers of PWM.
>>
>> Signed-off-by: Joonyoung Shim<jy0922.shim@samsung.com>
>> Signed-off-by: Kyungmin Park<kyungmin.park@samsung.com>
>> ---
>>   arch/arm/plat-samsung/pwm.c |    7 +++++++
>>   1 files changed, 7 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm/plat-samsung/pwm.c b/arch/arm/plat-samsung/pwm.c
>> index f37457c..dc1185d 100644
>> --- a/arch/arm/plat-samsung/pwm.c
>> +++ b/arch/arm/plat-samsung/pwm.c
>> @@ -299,6 +299,9 @@ static int s3c_pwm_probe(struct platform_device *pdev)
>>   		goto err_clk_tin;
>>   	}
>>
>> +	clk_enable(pwm->clk);
>> +	clk_enable(pwm->clk_div);
>> +
>>   	local_irq_save(flags);
>>
>>   	tcon = __raw_readl(S3C2410_TCON);
>> @@ -326,6 +329,8 @@ static int s3c_pwm_probe(struct platform_device *pdev)
>>   	return 0;
>>
>>    err_clk_tdiv:
>> +	clk_disable(pwm->clk_div);
>> +	clk_disable(pwm->clk);
>>   	clk_put(pwm->clk_div);
>>
>>    err_clk_tin:
>> @@ -340,6 +345,8 @@ static int __devexit s3c_pwm_remove(struct
>> platform_device *pdev)
>>   {
>>   	struct pwm_device *pwm = platform_get_drvdata(pdev);
>>
>> +	clk_disable(pwm->clk_div);
>> +	clk_disable(pwm->clk);
>>   	clk_put(pwm->clk_div);
>>   	clk_put(pwm->clk);
>>   	kfree(pwm);
>> --
>> 1.7.5.4
> Well, I wonder when this is needed. I think it should be enabled during
> kernel booting...

The exynos4 machine using just timer turns on "timer" clock in the past,
but "timer" clock is disable state when boot since MCT is used. MCT
doesn't control "timer" clock.

I think pwm driver should control(enable/disable) using clocks
regardless of their parents clock.

Thanks.