[PATCH 4.8 81/92] gpio: of: fix GPIO drivers with multiple gpio_chip for a single node

From: Greg Kroah-Hartman
Date: Thu Nov 17 2016 - 05:55:14 EST

4.8-stable review patch. If anyone has any objections, please let me know.


From: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>

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.

Fixes: 762c2e46c059 ("gpio: of: remove of_gpiochip_and_xlate() and struct gg_data")
Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Reported-by: Sylvain Lemieux <slemieux.tyco@xxxxxxxxx>
Tested-by: David Lechner <david@xxxxxxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -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) {
goto out;