Re: [PATCH v3 2/6] pwm: mediatek: fix pwm source clock selection

[Matthias Brugger]

On 06/30/2017 08:05 AM, Zhi Mao wrote:
> In original code, the pwm output frequency is not correct
> when set bit<3>=1 to PWMCON register.
>
> Signed-off-by: Zhi Mao <zhi.mao@xxxxxxxxxxxx>
> ---
>   drivers/pwm/pwm-mediatek.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
> index 5c11bc7..d08b5b3 100644
> --- a/drivers/pwm/pwm-mediatek.c
> +++ b/drivers/pwm/pwm-mediatek.c
> @@ -91,7 +91,7 @@ static int mtk_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>   	if (clkdiv > 7)
>   		return -EINVAL;
>   
> -	mtk_pwm_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | BIT(3) | clkdiv);
> +	mtk_pwm_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | clkdiv);

Just for clarification, BIT(15) enables old PWM mode, which ignores 
CLKSEL (BIT(3)). Therefore setting BIT(3) does not have any effect and 
can be discarded.

Am I correct? I took mt7623n datasheet for reference.

Regards,
Matthias

>   	mtk_pwm_writel(pc, pwm->hwpwm, PWMDWIDTH, period_ns / resolution);
>   	mtk_pwm_writel(pc, pwm->hwpwm, PWMTHRES, duty_ns / resolution);
>