mmc: omap_hsmmc: support deferred probing for GPIOs

If the CD/WP-GPIOs are not provided by the SoC's GPIO controller,
we need to handle the case where omap_hsmmc is probed earlier than
the GPIO controller chosen in the device tree.

Fix this by checking the return value of of_get_named_gpio against
-EPROBE_DEFER and passing it through to the probe function.
Signed-off-by: NJan Luebbe <jlu@pengutronix.de>
Acked-by: NBalaji T K <balajitk@ti.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

drivers/mmc/host/omap_hsmmc.c

@@ -1717,6 +1717,12 @@ static struct omap_mmc_platform_data *of_get_hsmmc_pdata(struct device *dev)
 	struct omap_mmc_platform_data *pdata;
 	struct device_node *np = dev->of_node;
 	u32 bus_width, max_freq;
+	int cd_gpio, wp_gpio;
+
+	cd_gpio = of_get_named_gpio(np, "cd-gpios", 0);
+	wp_gpio = of_get_named_gpio(np, "wp-gpios", 0);
+	if (cd_gpio == -EPROBE_DEFER || wp_gpio == -EPROBE_DEFER)
+		return ERR_PTR(-EPROBE_DEFER);
 
 	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)
@@ -1727,8 +1733,8 @@ static struct omap_mmc_platform_data *of_get_hsmmc_pdata(struct device *dev)
 
 	/* This driver only supports 1 slot */
 	pdata->nr_slots = 1;
-	pdata->slots[0].switch_pin = of_get_named_gpio(np, "cd-gpios", 0);
-	pdata->slots[0].gpio_wp = of_get_named_gpio(np, "wp-gpios", 0);
+	pdata->slots[0].switch_pin = cd_gpio;
+	pdata->slots[0].gpio_wp = wp_gpio;
 
 	if (of_find_property(np, "ti,non-removable", NULL)) {
 		pdata->slots[0].nonremovable = true;
@@ -1774,6 +1780,10 @@ static int omap_hsmmc_probe(struct platform_device *pdev)
 	match = of_match_device(of_match_ptr(omap_mmc_of_match), &pdev->dev);
 	if (match) {
 		pdata = of_get_hsmmc_pdata(&pdev->dev);
+
+		if (IS_ERR(pdata))
+			return PTR_ERR(pdata);
+
 		if (match->data) {
 			const u16 *offsetp = match->data;
 			pdata->reg_offset = *offsetp;