Re: [PATCH v4 1/1] pwm: imx27: workaround of the pwm output bug when decrease the duty cycle

[Marek Vasut]

On 9/9/24 9:38 PM, Frank Li wrote:

[...]

> +	 * Use __raw_writel() to minimize the interval between two writes to
> +	 * the SAR register to increase the fastest pwm frequency supported.
> +	 *
> +	 * When the PWM period is longer than 2us(or <500KHz), this workaround
> +	 * can solve this problem. No software workaround is available If PMW

PWM , typo

> +	 * period is shorter than IO write.
> +	 */
> +	c = clkrate * 1500;
> +	do_div(c, NSEC_PER_SEC);
> +
> +	local_irq_save(flags);
> +	val = FIELD_GET(MX3_PWMSR_FIFOAV, readl_relaxed(imx->mmio_base + MX3_PWMSR));
> +	if (duty_cycles < imx->duty_cycle && val < MX3_PWMSR_FIFOAV_2WORDS) {
> +		val = readl_relaxed(imx->mmio_base + MX3_PWMCNR);
> +		if ((val + c >= duty_cycles && val < imx->duty_cycle) ||
> +		    /*
> +		     * If counter is close to period, controller may roll over
> +		     * when next IO write.
> +		     */
> +		    val + c >= period_cycles)
> +			writel_relaxed(imx->duty_cycle, reg_sar);

Maybe use imx->mmio_base + MX3_PWMSAR instead of reg_sar here, to be 
consistent with imx->mmio_base + MX3_PWMSR above ?

> +	}
> +	writel_relaxed(duty_cycles, reg_sar);

Same here

> +	local_irq_restore(flags);
> +
>   	writel(period_cycles, imx->mmio_base + MX3_PWMPR);
[...]

Looks good otherwise, thanks !