quoted

+	struct fsl_pwm_chip *fpc;
+
+	fpc = to_fsl_chip(chip);
+
+	period_cycles = fsl_rate_to_cycles(fpc, period_ns);
+	if (period_cycles > 0xFFFF) {
+		dev_err(chip->dev, "required PWM period cycles(%lu) overflow "
+				"16-bits counter!\n", period_cycles);
+		return -EINVAL;
+	}
+
+	duty_cycles = fsl_rate_to_cycles(fpc, duty_ns);
+	if (duty_cycles >= 0xFFFF) {
+		dev_err(chip->dev, "required PWM duty cycles(%lu) overflow "
+				"16-bits counter!\n", duty_cycles);
+		return -EINVAL;
+	}

I'm not sure the error messages are all that useful. A -EINVAL error code
should make it pretty clear what the problem is.

Yes, it is.

But for the pwm leds, there hasn't any check about the return values, if
there is something wrong, we cannot get any information about this.

So I think this error messages are useful for this case.


--
Xiubo