On 05/11/12 22:03, Thierry Reding wrote:
> Cc'ing Roland and Alexandre. What do you guys think?
>
> On Mon, Nov 05, 2012 at 05:48:45PM +0100, Alban Bedel wrote:
>> Signed-off-by: Alban Bedel <alban.be...@avionic-design.de> ---
>> drivers/pwm/pwm-lpc32xx.c | 6 +++++- 1 files changed, 5
>> insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/pwm/pwm-lpc32xx.c
>> b/drivers/pwm/pwm-lpc32xx.c index adb87f0..a2704b8 100644 ---
>> a/drivers/pwm/pwm-lpc32xx.c +++ b/drivers/pwm/pwm-lpc32xx.c @@
>> -51,7 +51,11 @@ static int lpc32xx_pwm_config(struct pwm_chip
>> *chip, struct pwm_device *pwm,
>>
>> c = 256 * duty_ns; do_div(c, period_ns); - duty_cycles = c; + if
>> (c > 255) + c = 255; + if (c < 1) + c = 1; +
>> duty_cycles = 256
>> - c;
>>
>> writel(PWM_ENABLE | PWM_RELOADV(period_cycles) |
>> PWM_DUTY(duty_cycles), lpc32xx->base + (pwm->hwpwm << 2));
>
> Shouldn't duty_cycles rather be 255 - c, such that it can still be
> 0?
>
> Thierry
According to the Manual: [Low]/[High] = [PWM_DUTY] / [256-PWM_DUTY],
i.e., the PWM polarity inversion looks good.
However, as Thierry pointed out, the valid range 0..255 should be
maintained differently, maybe:
if (c > 255)
c = 255;
duty_cycles = 255 - c;
?
Thanks,
Roland
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