Re: [PATCH] ARM: SAMSUNG: Add clk enable/disable of pwm

[Kyungmin Park <kyungmin.park@xxxxxxxxxxx>]

On 11/3/11, Kyungmin Park <kyungmin.park@xxxxxxxxxxx> wrote:
> On 11/3/11, Joonyoung Shim <jy0922.shim@xxxxxxxxxxx> wrote:
>> 11/03/2011 04:46 PM, Kukjin Kim 쓴 글:
>>> Joonyoung Shim wrote:
>>>> 11/03/2011 10:59 AM, Kukjin Kim 쓴 글:
>>>>> 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@xxxxxxxxxxx>
>>>>>> Signed-off-by: Kyungmin Park<kyungmin.park@xxxxxxxxxxx>
>>>>>> ---
>>>>>>    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.
>>>>
>>> I mean, why that is disabled when kernel boot...
>>>
>>
>> Please see arch/arm/mach-exynos4/clock.c
>> There is "timers' clock in the clk init_clocks_off[].
One more, Don't assume some clocks are enabled at bootloader. user can
use any bootloader and any configuration.

Thanks.
>>
>> Thanks.
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>

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