On 23/09/2019 10.27, Uwe Kleine-König wrote: > On Mon, Sep 23, 2019 at 10:13:47AM +0200, Rasmus Villemoes wrote: >> >> >> + pol_bits = state->polarity == PWM_POLARITY_NORMAL ? >> + PERIOD_POLARITY_NORMAL : PERIOD_POLARITY_INVERSE; >> + >> writel(duty_cycles << 16, >> mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20); >> - writel(PERIOD_PERIOD(period_cycles) | PERIOD_POLARITY_NORMAL | PERIOD_CDIV(div), >> + writel(PERIOD_PERIOD(period_cycles) | pol_bits | PERIOD_CDIV(div), > > When will this affect the output? Only on the next start of a period, or > immediatly? Can it happen that this results in a mixed output (i.e. a > period that has already the new duty cycle from the line above but not > the new polarity (or period)? The data sheet says "Also, when the user reprograms the channel in this manner, the new register values will not take effect until the beginning of a new output period. This eliminates the potential for output glitches that could occur if the registers were updated while the channel was enabled and in the middle of a cycle.". So I think this should be ok. "this manner" refers to the registers being written in the proper order (first ACTIVEn, then PERIODn). Rasmus
