Patch "gpio: of: fix GPIO drivers with multiple gpio_chip for a single node" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

gpio: of: fix GPIO drivers with multiple gpio_chip for a single node

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
gpio-of-fix-gpio-drivers-with-multiple-gpio_chip-for-a-single-node.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Masahiro Yamada <[email protected]>
Date: Tue, 25 Oct 2016 10:47:44 +0900
Subject: gpio: of: fix GPIO drivers with multiple gpio_chip for a single node

From: Masahiro Yamada <[email protected]>

commit c7e9d39831a31682285cc31ddf7dd06c0fe59138 upstream.

Sylvain Lemieux reports the LPC32xx GPIO driver is broken since commit 762c2e46c059 ("gpio: of: remove of_gpiochip_and_xlate() and struct gg_data"). Probably, gpio-etraxfs.c and gpio-davinci.c are broken too.

Those drivers register multiple gpio_chip that are associated to a single OF node, and their own .of_xlate() checks if the passed gpio_chip is valid.

Now, the problem is of_find_gpiochip_by_node() returns the first gpio_chip found to match the given node. So, .of_xlate() fails, except for the first GPIO bank.

Reverting the commit could be a solution, but I do not want to go back to the mess of struct gg_data. Another solution here is to take the match by a node pointer and the success of .of_xlate(). It is a bit clumsy to call .of_xlate twice; for gpio_chip matching and for really getting the gpio_desc index. Perhaps, our long-term goal might be to convert the drivers to single chip registration, but this commit will solve the problem until then.

---
 drivers/gpio/gpiolib-of.c |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

@@ -26,14 +26,18 @@
 
 #include "gpiolib.h"
 
-static int of_gpiochip_match_node(struct gpio_chip *chip, void *data)
+static int of_gpiochip_match_node_and_xlate(struct gpio_chip *chip, void *data)
 {
-	return chip->gpiodev->dev.of_node == data;
+	struct of_phandle_args *gpiospec = data;
+
+	return chip->gpiodev->dev.of_node == gpiospec->np &&
+				chip->of_xlate(chip, gpiospec, NULL) >= 0;
 }
 
-static struct gpio_chip *of_find_gpiochip_by_node(struct device_node *np)
+static struct gpio_chip *of_find_gpiochip_by_xlate(
+					struct of_phandle_args *gpiospec)
 {
-	return gpiochip_find(np, of_gpiochip_match_node);
+	return gpiochip_find(gpiospec, of_gpiochip_match_node_and_xlate);
 }
 
 static struct gpio_desc *of_xlate_and_get_gpiod_flags(struct gpio_chip *chip,

@@ -79,7 +83,7 @@ struct gpio_desc *of_get_named_gpiod_fla
 		return ERR_PTR(ret);
 	}
 
-	chip = of_find_gpiochip_by_node(gpiospec.np);
+	chip = of_find_gpiochip_by_xlate(&gpiospec);
 	if (!chip) {
 		desc = ERR_PTR(-EPROBE_DEFER);
 		goto out;

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/gpio-of-fix-gpio-drivers-with-multiple-gpio_chip-for-a-single-node.patch