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Subject[PATCH] pinctrl: implement pinctrl deferred probing
Date
From: Linus Walleij <linus.walleij@linaro.org>

If drivers try to obtain pinctrl handles for a pin controller that
has not yet registered to the subsystem, we need to be able to
back out and retry with deferred probing. So let's return
-EPROBE_DEFER whenever this location fails.

Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
Documentation/pinctrl.txt | 5 +++++
drivers/pinctrl/core.c | 7 +++++--
drivers/pinctrl/devicetree.c | 4 ++--
3 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/Documentation/pinctrl.txt b/Documentation/pinctrl.txt
index eb46b1c..4431c3e7 100644
--- a/Documentation/pinctrl.txt
+++ b/Documentation/pinctrl.txt
@@ -1043,6 +1043,11 @@ quickly poking some registers.
The pins are allocated for your device when you issue the pinctrl_get() call,
after this you should be able to see this in the debugfs listing of all pins.

+NOTE: the pinctrl system will return -EPROBE_DEFER if it cannot find the
+requested pinctrl handles, for example if the pinctrl driver has not yet
+registered. Thus make sure that the error path in your driver gracefully
+cleans up and is ready to retry the probing later in the startup process.
+

System pin control hogging
==========================
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 7ff8690..3ae00ab 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -521,8 +521,11 @@ static int add_setting(struct pinctrl *p, struct pinctrl_map const *map)
dev_err(p->dev, "unknown pinctrl device %s in map entry",
map->ctrl_dev_name);
kfree(setting);
- /* Eventually, this should trigger deferred probe */
- return -ENODEV;
+ /*
+ * OK let us guess that the driver is not there yet, and
+ * let's defer obtaining this pinctrl handle to later...
+ */
+ return -EPROBE_DEFER;
}

switch (map->type) {
diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c
index 5ef2feb..8833538 100644
--- a/drivers/pinctrl/devicetree.c
+++ b/drivers/pinctrl/devicetree.c
@@ -124,8 +124,8 @@ static int dt_to_map_one_config(struct pinctrl *p, const char *statename,
dev_err(p->dev, "could not find pctldev for node %s\n",
np_config->full_name);
of_node_put(np_pctldev);
- /* FIXME: This should trigger deferrered probe */
- return -ENODEV;
+ /* OK let's just assume this will appear later then */
+ return -EPROBE_DEFER;
}
pctldev = find_pinctrl_by_of_node(np_pctldev);
if (pctldev)
--
1.7.9.2


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