[U-Boot] [PATCH 3/9 v2] Exynos: pwm: Fix two bugs in the exynos pwm configuration code

[Akshay Saraswat]

Hi Minkyu,

Thanks for your comments.

>Dear Akshay,
>
>On 28/02/13 19:59, Akshay Saraswat wrote:
>> First, the "div" value was being used incorrectly to compute the frequency of
>> the PWM timer. The value passed in is a constant which reflects the value
>> that would be found in a configuration register, 0 to 4. That should
>> correspond to a scaling factor of 1, 2, 4, 8, or 16, 1 << div, but div + 1 was
>> being used instead.
>> 
>> @@ -167,20 +167,24 @@ int pwm_init(int pwm_id, int div, int invert)
>>  	val |= (div & 0xf) << MUX_DIV_SHIFT(pwm_id);
>>  	writel(val, &pwm->tcfg1);
>>  
>> -	timer_rate_hz = get_pwm_clk() / ((prescaler + 1) *
>> -			(div + 1));
>> +	if (pwm_id == 4) {
>> +		/*
>> +		 * TODO(sjg): Use this as a countdown timer for now. We count
>> +		 * down from the maximum value to 0, then reset.
>> +		 */
>> +		ticks_per_period = -1UL;
>> +	} else {
>> +		const unsigned long pwm_hz = 1000;
>> +		unsigned long timer_rate_hz = get_pwm_clk() /
>> +			((prescaler + 1) * (1 << div));
>
>good catch. thanks.
>
>>  
>> -	timer_rate_hz = timer_rate_hz / CONFIG_SYS_HZ;
>> +		ticks_per_period = timer_rate_hz / pwm_hz;
>
>why don't you use CONFIG_SYS_HZ?
>pwm_hz seems to constant.

CONFIG_SYS_HZ may change with boards and as per needs.
But requirement here is for a constant value 1000
for all calculations which should remain 1000 only.
That's why using pwm_hz and not CONFIG_SYS_HZ.

>
>> +	}
>>  
>>  	/* set count value */
>>  	offset = pwm_id * 3;
>>  
>> -	/*
>> -	 * TODO(sjg): Use this as a countdown timer for now. We count down
>> -	 * from the maximum value to 0, then reset.
>> -	 */
>> -	timer_rate_hz = -1;
>> -	writel(timer_rate_hz, &pwm->tcntb0 + offset);
>> +	writel(ticks_per_period, &pwm->tcntb0 + offset);
>>  
>>  	val = readl(&pwm->tcon) & ~(0xf << TCON_OFFSET(pwm_id));
>>  	if (invert && (pwm_id < 4))
>> 
>
>Thanks,
>Minkyu Kang.
>

Regards,
Akshay Saraswat