On Fri, Oct 12, 2018 at 03:04:48PM +0000, Vokáč Michal wrote:

On 12.10.2018 10:57, Uwe Kleine-König wrote:

quoted

On Wed, Oct 10, 2018 at 09:33:26AM +0000, Vokáč Michal wrote:

[...]

quoted

quoted

+static int imx_pwm_init_pinctrl_info(struct imx_chip *imx_chip,
+		struct platform_device *pdev)
+{
+	imx_chip->pinctrl = devm_pinctrl_get(&pdev->dev);
+	if (!imx_chip->pinctrl || IS_ERR(imx_chip->pinctrl)) {
+		dev_info(&pdev->dev, "can not get pinctrl\n");
+		return PTR_ERR(imx_chip->pinctrl);
+	}
+
+	imx_chip->pinctrl_pins_pwm = pinctrl_lookup_state(imx_chip->pinctrl,
+			"pwm");
+	imx_chip->pinctrl_pins_gpio = pinctrl_lookup_state(imx_chip->pinctrl,
+			"gpio");
+	imx_chip->pwm_gpiod = devm_gpiod_get_optional(&pdev->dev, "pwm",
+			GPIOD_IN);
+
+	if (PTR_ERR(imx_chip->pwm_gpiod) == -EPROBE_DEFER) {

You must not use PTR_ERR on a value that might not contain an error
pointer.

OK, thank you for valuable info.
So it seems like the I2C folks are in troubles as well:

	https://elixir.bootlin.com/linux/latest/source/drivers/i2c/busses/i2c-imx.c#L996

There's nothing inherently wrong with doing it like the above, just
maybe slightly unusual. PTR_ERR() is really just casting from a pointer
to an integer, so if the pointer happens to contain the value
-EPROBE_DEFER, then the above will be true. If it contains a valid
pointer, the above will be false, so it does exactly what you want.

Perhaps a more idiomatic way to write this would be:

	if (IS_ERR(imx_chip->pwm_gpiod)) {
		if (PTR_ERR(imx_chip->pwm_gpiod) == -EPROBE_DEFER)
			return -EPROBE_DEFER;
	}

But that's not much clearer than what you have, so feel free to keep it
that way.

Thierry