[v2,1/3] gpio: defer probe if pinctrl cannot be found

When an OF node has a pin range for its GPIOs, return -EPROBE_DEFER if
the pin controller isn't available.

Otherwise, the GPIO range wouldn't be set at all unless the pin
controller probed always before the GPIO chip.

With this change, the probe of the GPIO chip will be deferred and will
be retried at a later point, hopefully once the pin controller has been
registered and probed already.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---

Changes in v2:
- Don't defer probe if the pinctrl node is disabled

 drivers/gpio/gpiolib-of.c | 27 ++++++++++++++++++---------
 drivers/gpio/gpiolib.c    |  5 ++++-
 include/linux/of_gpio.h   |  4 ++--
 3 files changed, 24 insertions(+), 12 deletions(-)

On 14 July 2015 at 10:29, Tomeu Vizoso <tomeu.vizoso@collabora.com> wrote:
> When an OF node has a pin range for its GPIOs, return -EPROBE_DEFER if
> the pin controller isn't available.
>
> Otherwise, the GPIO range wouldn't be set at all unless the pin
> controller probed always before the GPIO chip.
>
> With this change, the probe of the GPIO chip will be deferred and will
> be retried at a later point, hopefully once the pin controller has been
> registered and probed already.

Ping :)

Thanks,

Tomeu

> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> ---
>
> Changes in v2:
> - Don't defer probe if the pinctrl node is disabled
>
>  drivers/gpio/gpiolib-of.c | 27 ++++++++++++++++++---------
>  drivers/gpio/gpiolib.c    |  5 ++++-
>  include/linux/of_gpio.h   |  4 ++--
>  3 files changed, 24 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
> index 9a0ec48a4737..4e1f73b9136a 100644
> --- a/drivers/gpio/gpiolib-of.c
> +++ b/drivers/gpio/gpiolib-of.c
> @@ -338,7 +338,7 @@ void of_mm_gpiochip_remove(struct of_mm_gpio_chip *mm_gc)
>  EXPORT_SYMBOL(of_mm_gpiochip_remove);
>
>  #ifdef CONFIG_PINCTRL
> -static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
> +static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
>  {
>         struct device_node *np = chip->of_node;
>         struct of_phandle_args pinspec;
> @@ -349,7 +349,7 @@ static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
>         struct property *group_names;
>
>         if (!np)
> -               return;
> +               return 0;
>
>         group_names = of_find_property(np, group_names_propname, NULL);
>
> @@ -361,7 +361,7 @@ static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
>
>                 pctldev = of_pinctrl_get(pinspec.np);
>                 if (!pctldev)
> -                       break;
> +                       return -EPROBE_DEFER;
>
>                 if (pinspec.args[2]) {
>                         if (group_names) {
> @@ -381,7 +381,7 @@ static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
>                                         pinspec.args[1],
>                                         pinspec.args[2]);
>                         if (ret)
> -                               break;
> +                               return ret;
>                 } else {
>                         /* npins == 0: special range */
>                         if (pinspec.args[1]) {
> @@ -411,32 +411,41 @@ static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
>                         ret = gpiochip_add_pingroup_range(chip, pctldev,
>                                                 pinspec.args[0], name);
>                         if (ret)
> -                               break;
> +                               return ret;
>                 }
>         }
> +
> +       return 0;
>  }
>
>  #else
> -static void of_gpiochip_add_pin_range(struct gpio_chip *chip) {}
> +static int of_gpiochip_add_pin_range(struct gpio_chip *chip) { return 0; }
>  #endif
>
> -void of_gpiochip_add(struct gpio_chip *chip)
> +int of_gpiochip_add(struct gpio_chip *chip)
>  {
> +       int status;
> +
>         if ((!chip->of_node) && (chip->dev))
>                 chip->of_node = chip->dev->of_node;
>
>         if (!chip->of_node)
> -               return;
> +               return 0;
>
>         if (!chip->of_xlate) {
>                 chip->of_gpio_n_cells = 2;
>                 chip->of_xlate = of_gpio_simple_xlate;
>         }
>
> -       of_gpiochip_add_pin_range(chip);
> +       status = of_gpiochip_add_pin_range(chip);
> +       if (status)
> +               return status;
> +
>         of_node_get(chip->of_node);
>
>         of_gpiochip_scan_hogs(chip);
> +
> +       return 0;
>  }
>
>  void of_gpiochip_remove(struct gpio_chip *chip)
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index bf4bd1d120c3..a8cab335c0cc 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -287,7 +287,10 @@ int gpiochip_add(struct gpio_chip *chip)
>         INIT_LIST_HEAD(&chip->pin_ranges);
>  #endif
>
> -       of_gpiochip_add(chip);
> +       status = of_gpiochip_add(chip);
> +       if (status)
> +               goto err_remove_chip;
> +
>         acpi_gpiochip_add(chip);
>
>         status = gpiochip_sysfs_register(chip);
> diff --git a/include/linux/of_gpio.h b/include/linux/of_gpio.h
> index 69dbe312b11b..f3191828f037 100644
> --- a/include/linux/of_gpio.h
> +++ b/include/linux/of_gpio.h
> @@ -54,7 +54,7 @@ extern int of_mm_gpiochip_add(struct device_node *np,
>                               struct of_mm_gpio_chip *mm_gc);
>  extern void of_mm_gpiochip_remove(struct of_mm_gpio_chip *mm_gc);
>
> -extern void of_gpiochip_add(struct gpio_chip *gc);
> +extern int of_gpiochip_add(struct gpio_chip *gc);
>  extern void of_gpiochip_remove(struct gpio_chip *gc);
>  extern int of_gpio_simple_xlate(struct gpio_chip *gc,
>                                 const struct of_phandle_args *gpiospec,
> @@ -76,7 +76,7 @@ static inline int of_gpio_simple_xlate(struct gpio_chip *gc,
>         return -ENOSYS;
>  }
>
> -static inline void of_gpiochip_add(struct gpio_chip *gc) { }
> +static inline int of_gpiochip_add(struct gpio_chip *gc) { return 0; }
>  static inline void of_gpiochip_remove(struct gpio_chip *gc) { }
>
>  #endif /* CONFIG_OF_GPIO */
> --
> 2.4.3
>
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On Tue, Jul 14, 2015 at 10:29 AM, Tomeu Vizoso
<tomeu.vizoso@collabora.com> wrote:

> When an OF node has a pin range for its GPIOs, return -EPROBE_DEFER if
> the pin controller isn't available.
>
> Otherwise, the GPIO range wouldn't be set at all unless the pin
> controller probed always before the GPIO chip.
>
> With this change, the probe of the GPIO chip will be deferred and will
> be retried at a later point, hopefully once the pin controller has been
> registered and probed already.
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> ---
>
> Changes in v2:
> - Don't defer probe if the pinctrl node is disabled

Sorry for the delay.

This looks like the right thing to do, I was just worried that it would have
undesired semantic or probe order effects on some platforms, but I think
this is one of these cases where I just have to apply this and see what
happens when people test it in linux-next.

So, patch applied.

Yours,
Linus Walleij
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