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[PATCH V2 3/5] gpio: of: Return error if gpio hog configuration failed

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  [PATCH V2 3/5] gpio: of: Return error if gpio hog configuration failed Laxman Dewangan <ldewangan@nvidia.com> - 2016-03-11 15:00 +0100
    Re: [PATCH V2 3/5] gpio: of: Return error if gpio hog configuration failed Linus Walleij <linus.walleij@linaro.org> - 2016-03-15 15:20 +0100
      Re: [PATCH V2 3/5] gpio: of: Return error if gpio hog configuration  failed Laxman Dewangan <ldewangan@nvidia.com> - 2016-03-16 12:30 +0100

#1355919 — [PATCH V2 3/5] gpio: of: Return error if gpio hog configuration failed

If GPIO hog configuration failed while adding OF based
gpiochip() then return the error instead of ignoring it.

This helps of properly handling the gpio driver dependency.

When adding the gpio hog nodes for NVIDIA's Tegra210 platforms,
the gpio_hogd() fails with EPROBE_DEFER because pinctrl is not
ready at this time and gpio_request() for Tegra GPIO driver
returns error. The error was not causing the Tegra GPIO driver
to fail as the error was getting ignored.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Cc: Benoit Parrot <bparrot@ti.com>
Cc: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>

---
Changes from V1:
- Add Thierry's ack.
---
 drivers/gpio/gpiolib-of.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index f2ba1a4..d81dbd8 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -201,14 +201,16 @@ static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
  *
  * This is only used by of_gpiochip_add to request/set GPIO initial
  * configuration.
+ * It retures error if it fails otherwise 0 on success.
  */
-static void of_gpiochip_scan_gpios(struct gpio_chip *chip)
+static int of_gpiochip_scan_gpios(struct gpio_chip *chip)
 {
 	struct gpio_desc *desc = NULL;
 	struct device_node *np;
 	const char *name;
 	enum gpio_lookup_flags lflags;
 	enum gpiod_flags dflags;
+	int ret;
 
 	for_each_available_child_of_node(chip->of_node, np) {
 		if (!of_property_read_bool(np, "gpio-hog"))
@@ -218,9 +220,12 @@ static void of_gpiochip_scan_gpios(struct gpio_chip *chip)
 		if (IS_ERR(desc))
 			continue;
 
-		if (gpiod_hog(desc, name, lflags, dflags))
-			continue;
+		ret = gpiod_hog(desc, name, lflags, dflags);
+		if (ret < 0)
+			return ret;
 	}
+
+	return 0;
 }
 
 /**
@@ -442,9 +447,7 @@ int of_gpiochip_add(struct gpio_chip *chip)
 
 	of_node_get(chip->of_node);
 
-	of_gpiochip_scan_gpios(chip);
-
-	return 0;
+	return of_gpiochip_scan_gpios(chip);
 }
 
 void of_gpiochip_remove(struct gpio_chip *chip)
-- 
2.1.4

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#1358063

On Fri, Mar 11, 2016 at 2:43 PM, Laxman Dewangan <ldewangan@nvidia.com> wrote:

> If GPIO hog configuration failed while adding OF based
> gpiochip() then return the error instead of ignoring it.
>
> This helps of properly handling the gpio driver dependency.
>
> When adding the gpio hog nodes for NVIDIA's Tegra210 platforms,
> the gpio_hogd() fails with EPROBE_DEFER because pinctrl is not
> ready at this time and gpio_request() for Tegra GPIO driver
> returns error. The error was not causing the Tegra GPIO driver
> to fail as the error was getting ignored.
>
> Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
> Cc: Benoit Parrot <bparrot@ti.com>
> Cc: Alexandre Courbot <acourbot@nvidia.com>
> Reviewed-by: Thierry Reding <treding@nvidia.com>

Oops is this something I should apply for fixes and tag
for stable?

Yours,
Linus Walleij

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#1358890 — Re: [PATCH V2 3/5] gpio: of: Return error if gpio hog configuration failed

On Tuesday 15 March 2016 07:42 PM, Linus Walleij wrote:
> On Fri, Mar 11, 2016 at 2:43 PM, Laxman Dewangan <ldewangan@nvidia.com> wrote:
>
>> If GPIO hog configuration failed while adding OF based
>> gpiochip() then return the error instead of ignoring it.
>>
>> This helps of properly handling the gpio driver dependency.
>>
>> When adding the gpio hog nodes for NVIDIA's Tegra210 platforms,
>> the gpio_hogd() fails with EPROBE_DEFER because pinctrl is not
>> ready at this time and gpio_request() for Tegra GPIO driver
>> returns error. The error was not causing the Tegra GPIO driver
>> to fail as the error was getting ignored.
>>
>> Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
>> Cc: Benoit Parrot <bparrot@ti.com>
>> Cc: Alexandre Courbot <acourbot@nvidia.com>
>> Reviewed-by: Thierry Reding <treding@nvidia.com>
> Oops is this something I should apply for fixes and tag
> for stable?
>

I dont think that it is needed for stable as this is newly added feature.

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