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[].
>
> Thanks.
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