On 2023/10/20 19:25, Uwe Kleine-König wrote: >> + void __iomem *base = pwm->data->get_ch_base ? >> + pwm->data->get_ch_base(pwm->regs, dev->hwpwm) : pwm->regs; >> + u32 period_data, duty_data, ctrl_data; >> + >> + period_data = readl(REG_OCPWM_LRC(base)); >> + duty_data = readl(REG_OCPWM_HRC(base)); >> + ctrl_data = readl(REG_OCPWM_CTRL(base)); >> + >> + state->period = DIV_ROUND_CLOSEST_ULL((u64)period_data * NSEC_PER_SEC, pwm->clk_rate); >> + state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_data * NSEC_PER_SEC, pwm->clk_rate); > > Please test your driver with PWM_DEBUG enabled. The rounding is wrong > here. > Hi Uwe, The conclusion after checking is: when the period or duty_cycle value set by the user is not divisible (1000000000/49.5M), there will be an error. This error is due to hardware accuracy. So why is rounding is wrong? rockchip also has a similar implementation drivers/pwm/ pwm-rockchip.c Best regards, William
