On Thu, June 25, 2020 1:28 AM, Uwe Kleine-König
> On Wed, Jun 24, 2020 at 03:39:52PM +0000, Roy Im wrote:
> > On Wed, Jun 24, 2020 at 10:37 PM, Uwe Kleine-König wrote:
> > > On Wed, Jun 24, 2020 at 12:04:24PM +0900, Roy Im wrote:
> > > > period2freq = 1000000 / state.period;
> > > > if (period2freq < DA7280_MIN_PWM_FREQ_KHZ ||
> > > > period2freq > DA7280_MAX_PWM_FREQ_KHZ) {
> > > > dev_err(dev, "Unsupported PWM frequency (%u)\n",
> > > > period2freq);
> > > > return -EINVAL;
> > > > }
> > > > If you look ok, let me update this so.
> > >
> > > looks fine.
> > >
> > > Note that you don't need the division if you check for:
> > >
> > > if (state.period > 100000 || state.period < 4000) {
> > > ...
> > >
> > > (maybe the compiler is already clever enough to get rid of the division
> > > for you, but then the check is:
> > >
> > > if (state.period > 100000 || state.period < 3985) {
> > >
> > > because of rounding errors.)
> >
> > OK, you are right, that will be better. So let me change that as below
> > if you look fine.
>
> I look fine, the code however is wrong. :-)
>
> > /* Check PWM period, PWM freq = 1000000 / state.period.
> > * The valid PWM freq range: 10k ~ 250kHz.
> > */
> > if (state.period > 100000 || state.period < 3985) {
>
> You want 4000 here ---------------------------------^^^^, don't you?
Yes, it is now based on period, not frequency. You are right.
4000 is correct now. Thanks.
>
> > dev_err(dev, "Unsupported PWM period (%u)\n",
> > state.period);
> > return -EINVAL;
> > }
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K. | Uwe Kleine-König |
> Industrial Linux Solutions | https://www.pengutronix.de/ |
