Re: [PATCH v9 2/8] pwm: pca9685: Support hardware readout

[Uwe Kleine-König]

Hello,

On Thu, Apr 15, 2021 at 02:14:49PM +0200, Clemens Gruber wrote:
> Implement .get_state to read-out the current hardware state.
> 
> The hardware readout may return slightly different values than those
> that were set in apply due to the limited range of possible prescale and
> counter register values.
> 
> Also note that although the datasheet mentions 200 Hz as default
> frequency when using the internal 25 MHz oscillator, the calculated
> period from the default prescaler register setting of 30 is 5079040ns.
> 
> Signed-off-by: Clemens Gruber <clemens.gruber@xxxxxxxxxxxx>
> ---
> Changes since v8:
> - As we left the math in apply as-is, use DIV_ROUND_DOWN in get_state

I first thought this was wrong, because .apply uses ROUND_CLOSEST for
period and ROUND_UP for duty. But as the calculation for period is exact
this doesn't matter and round-down is indeed correct here.

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>

Thanks
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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