pinctrl: fix error path in pinconf_map_to_setting()

The code was using the union member
setting->data.configs.group_or_pin to store a potential
error code, but since that member is unsigned the
< 0 comparison was not true, letting errors pass through,
ending up as mapped to pin "-22". Fix this up and print
the error.

Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinconf.c

@@ -282,21 +282,28 @@ int pinconf_map_to_setting(struct pinctrl_map const *map,
 			  struct pinctrl_setting *setting)
 {
 	struct pinctrl_dev *pctldev = setting->pctldev;
+	int pin;
 
 	switch (setting->type) {
 	case PIN_MAP_TYPE_CONFIGS_PIN:
-		setting->data.configs.group_or_pin =
-			pin_get_from_name(pctldev,
+		pin = pin_get_from_name(pctldev,
 					map->data.configs.group_or_pin);
-		if (setting->data.configs.group_or_pin < 0)
-			return setting->data.configs.group_or_pin;
+		if (pin < 0) {
+			dev_err(pctldev->dev, "could not map pin config for \"%s\"",
+				map->data.configs.group_or_pin);
+			return pin;
+		}
+		setting->data.configs.group_or_pin = pin;
 		break;
 	case PIN_MAP_TYPE_CONFIGS_GROUP:
-		setting->data.configs.group_or_pin =
-			pinctrl_get_group_selector(pctldev,
+		pin = pinctrl_get_group_selector(pctldev,
 					 map->data.configs.group_or_pin);
-		if (setting->data.configs.group_or_pin < 0)
-			return setting->data.configs.group_or_pin;
+		if (pin < 0) {
+			dev_err(pctldev->dev, "could not map group config for \"%s\"",
+				map->data.configs.group_or_pin);
+			return pin;
+		}
+		setting->data.configs.group_or_pin = pin;
 		break;
 	default:
 		return -EINVAL;