[PATCH v2] gpio: fix "gpio-line-names" property retrieval

[chleroy]

Following commit 9427ecbed46cc ("gpio: Rework of_gpiochip_set_names()
to use device property accessors"), "gpio-line-names" DT property is
not retrieved anymore when chip->parent is not set by the driver.
This is due to OF based property reads having been replaced by device
based property reads.

This patch fixes that by making use of
fwnode_property_read_string_array() instead of
device_property_read_string_array() and handing over either
of_fwnode_handle(chip->of_node) or dev_fwnode(chip->parent)
to that function.

Fixes: 9427ecbed46cc ("gpio: Rework of_gpiochip_set_names() to use device property accessors")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
 drivers/gpio/gpiolib-acpi.c    |  2 +-
 drivers/gpio/gpiolib-devprop.c | 17 +++++++----------
 drivers/gpio/gpiolib-of.c      |  3 ++-
 drivers/gpio/gpiolib.h         |  3 ++-
 4 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index eb4528c87c0b..d6f3d9ee1350 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -1074,7 +1074,7 @@ void acpi_gpiochip_add(struct gpio_chip *chip)
 	}
 
 	if (!chip->names)
-		devprop_gpiochip_set_names(chip);
+		devprop_gpiochip_set_names(chip, dev_fwnode(chip->parent));
 
 	acpi_gpiochip_request_regions(acpi_gpio);
 	acpi_gpiochip_scan_gpios(acpi_gpio);
diff --git a/drivers/gpio/gpiolib-devprop.c b/drivers/gpio/gpiolib-devprop.c
index 27f383bda7d9..f748aa3e77f7 100644
--- a/drivers/gpio/gpiolib-devprop.c
+++ b/drivers/gpio/gpiolib-devprop.c
@@ -19,30 +19,27 @@
 /**
  * devprop_gpiochip_set_names - Set GPIO line names using device properties
  * @chip: GPIO chip whose lines should be named, if possible
+ * @fwnode: Property Node containing the gpio-line-names property
  *
  * Looks for device property "gpio-line-names" and if it exists assigns
  * GPIO line names for the chip. The memory allocated for the assigned
  * names belong to the underlying firmware node and should not be released
  * by the caller.
  */
-void devprop_gpiochip_set_names(struct gpio_chip *chip)
+void devprop_gpiochip_set_names(struct gpio_chip *chip,
+				const struct fwnode_handle *fwnode)
 {
 	struct gpio_device *gdev = chip->gpiodev;
 	const char **names;
 	int ret, i;
 
-	if (!chip->parent) {
-		dev_warn(&gdev->dev, "GPIO chip parent is NULL\n");
-		return;
-	}
-
-	ret = device_property_read_string_array(chip->parent, "gpio-line-names",
+	ret = fwnode_property_read_string_array(fwnode, "gpio-line-names",
 						NULL, 0);
 	if (ret < 0)
 		return;
 
 	if (ret != gdev->ngpio) {
-		dev_warn(chip->parent,
+		dev_warn(&gdev->dev,
 			 "names %d do not match number of GPIOs %d\n", ret,
 			 gdev->ngpio);
 		return;
@@ -52,10 +49,10 @@ void devprop_gpiochip_set_names(struct gpio_chip *chip)
 	if (!names)
 		return;
 
-	ret = device_property_read_string_array(chip->parent, "gpio-line-names",
+	ret = fwnode_property_read_string_array(fwnode, "gpio-line-names",
 						names, gdev->ngpio);
 	if (ret < 0) {
-		dev_warn(chip->parent, "failed to read GPIO line names\n");
+		dev_warn(&gdev->dev, "failed to read GPIO line names\n");
 		kfree(names);
 		return;
 	}
diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index e0d59e61b52f..72a0695d2ac3 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -493,7 +493,8 @@ int of_gpiochip_add(struct gpio_chip *chip)
 
 	/* If the chip defines names itself, these take precedence */
 	if (!chip->names)
-		devprop_gpiochip_set_names(chip);
+		devprop_gpiochip_set_names(chip,
+					   of_fwnode_handle(chip->of_node));
 
 	of_node_get(chip->of_node);
 
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index af48322839c3..6c44d1652139 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -228,7 +228,8 @@ static inline int gpio_chip_hwgpio(const struct gpio_desc *desc)
 	return desc - &desc->gdev->descs[0];
 }
 
-void devprop_gpiochip_set_names(struct gpio_chip *chip);
+void devprop_gpiochip_set_names(struct gpio_chip *chip,
+				const struct fwnode_handle *fwnode);
 
 /* With descriptor prefix */
 
-- 
2.13.3