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Subject[PATCH] pinctrl: core: Fix regression caused by delayed work for hogs
Date
Commit df61b366af26 ("pinctrl: core: Use delayed work for hogs") caused a
regression at least with sh-pfc that is also a GPIO controller as
noted by Geert Uytterhoeven <geert@linux-m68k.org>.

As the original pinctrl_register() has issues calling pin controller
driver functions early before the controller has finished registering,
we can't just revert commit df61b366af26. That would break the drivers
using GENERIC_PINCTRL_GROUPS or GENERIC_PINMUX_FUNCTIONS.

So let's fix the issue with the following steps as a single patch:

1. Revert the late_init parts of commit df61b366af26.

The late_init clearly won't work and we have to just give up
on fixing pinctrl_register() for GENERIC_PINCTRL_GROUPS and
GENERIC_PINMUX_FUNCTIONS.

2. Split pinctrl_register() into two parts

By splitting pinctrl_register() into pinctrl_init_controller()
and pinctrl_create_and_start() we have better control over when
it's safe to call pinctrl_create().

3. Introduce a new pinctrl_register_and_init() function

As suggested by Linus Walleij <linus.walleij@linaro.org>, we
can just introduce a new function for the controllers that need
pinctrl_create() called later.

4. Convert the four known problem cases to use new function

Let's convert pinctrl-imx, pinctrl-single, sh-pfc and ti-iodelay
to use the new function to fix the issues. The rest of the drivers
can be converted later. Let's also update Documentation/pinctrl.txt
accordingly because of the known issues with pinctrl_register().

Fixes: df61b366af26 ("pinctrl: core: Use delayed work for hogs")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
---
Documentation/pinctrl.txt | 4 +-
drivers/pinctrl/core.c | 201 ++++++++++++++++++++++----------
drivers/pinctrl/core.h | 2 -
drivers/pinctrl/freescale/pinctrl-imx.c | 8 +-
drivers/pinctrl/pinctrl-single.c | 5 +-
drivers/pinctrl/sh-pfc/pinctrl.c | 4 +-
drivers/pinctrl/ti/pinctrl-ti-iodelay.c | 5 +-
include/linux/pinctrl/pinctrl.h | 15 +++
8 files changed, 165 insertions(+), 79 deletions(-)

diff --git a/Documentation/pinctrl.txt b/Documentation/pinctrl.txt
--- a/Documentation/pinctrl.txt
+++ b/Documentation/pinctrl.txt
@@ -79,9 +79,7 @@ int __init foo_probe(void)
{
struct pinctrl_dev *pctl;

- pctl = pinctrl_register(&foo_desc, <PARENT>, NULL);
- if (!pctl)
- pr_err("could not register foo pin driver\n");
+ return pinctrl_register_and_init(&foo_desc, <PARENT>, NULL, &pctl);
}

To enable the pinctrl subsystem and the subgroups for PINMUX and PINCONF and
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -1905,59 +1905,14 @@ static int pinctrl_check_ops(struct pinctrl_dev *pctldev)
}

/**
- * pinctrl_late_init() - finish pin controller device registration
- * @work: work struct
- */
-static void pinctrl_late_init(struct work_struct *work)
-{
- struct pinctrl_dev *pctldev;
-
- pctldev = container_of(work, struct pinctrl_dev, late_init.work);
-
- /*
- * If the pin controller does NOT have hogs, this will report an
- * error and we skip over this entire branch. This is why we can
- * call this function directly when we do not have hogs on the
- * device.
- */
- pctldev->p = create_pinctrl(pctldev->dev, pctldev);
- if (!IS_ERR(pctldev->p)) {
- kref_get(&pctldev->p->users);
- pctldev->hog_default =
- pinctrl_lookup_state(pctldev->p, PINCTRL_STATE_DEFAULT);
- if (IS_ERR(pctldev->hog_default)) {
- dev_dbg(pctldev->dev,
- "failed to lookup the default state\n");
- } else {
- if (pinctrl_select_state(pctldev->p,
- pctldev->hog_default))
- dev_err(pctldev->dev,
- "failed to select default state\n");
- }
-
- pctldev->hog_sleep =
- pinctrl_lookup_state(pctldev->p,
- PINCTRL_STATE_SLEEP);
- if (IS_ERR(pctldev->hog_sleep))
- dev_dbg(pctldev->dev,
- "failed to lookup the sleep state\n");
- }
-
- mutex_lock(&pinctrldev_list_mutex);
- list_add_tail(&pctldev->node, &pinctrldev_list);
- mutex_unlock(&pinctrldev_list_mutex);
-
- pinctrl_init_device_debugfs(pctldev);
-}
-
-/**
- * pinctrl_register() - register a pin controller device
+ * pinctrl_init_controller() - init a pin controller device
* @pctldesc: descriptor for this pin controller
* @dev: parent device for this pin controller
* @driver_data: private pin controller data for this pin controller
*/
-struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
- struct device *dev, void *driver_data)
+struct pinctrl_dev *pinctrl_init_controller(struct pinctrl_desc *pctldesc,
+ struct device *dev,
+ void *driver_data)
{
struct pinctrl_dev *pctldev;
int ret;
@@ -1983,7 +1938,6 @@ struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
INIT_RADIX_TREE(&pctldev->pin_function_tree, GFP_KERNEL);
#endif
INIT_LIST_HEAD(&pctldev->gpio_ranges);
- INIT_DELAYED_WORK(&pctldev->late_init, pinctrl_late_init);
pctldev->dev = dev;
mutex_init(&pctldev->mutex);

@@ -2018,17 +1972,6 @@ struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
goto out_err;
}

- /*
- * If the device has hogs we want the probe() function of the driver
- * to complete before we go in and hog them and add the pin controller
- * to the list of controllers. If it has no hogs, we can just complete
- * the registration immediately.
- */
- if (pinctrl_dt_has_hogs(pctldev))
- schedule_delayed_work(&pctldev->late_init, 0);
- else
- pinctrl_late_init(&pctldev->late_init.work);
-
return pctldev;

out_err:
@@ -2036,8 +1979,107 @@ struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
kfree(pctldev);
return ERR_PTR(ret);
}
+
+static int pinctrl_create_and_start(struct pinctrl_dev *pctldev)
+{
+ pctldev->p = create_pinctrl(pctldev->dev, pctldev);
+ if (!IS_ERR(pctldev->p)) {
+ kref_get(&pctldev->p->users);
+ pctldev->hog_default =
+ pinctrl_lookup_state(pctldev->p, PINCTRL_STATE_DEFAULT);
+ if (IS_ERR(pctldev->hog_default)) {
+ dev_dbg(pctldev->dev,
+ "failed to lookup the default state\n");
+ } else {
+ if (pinctrl_select_state(pctldev->p,
+ pctldev->hog_default))
+ dev_err(pctldev->dev,
+ "failed to select default state\n");
+ }
+
+ pctldev->hog_sleep =
+ pinctrl_lookup_state(pctldev->p,
+ PINCTRL_STATE_SLEEP);
+ if (IS_ERR(pctldev->hog_sleep))
+ dev_dbg(pctldev->dev,
+ "failed to lookup the sleep state\n");
+ }
+
+ mutex_lock(&pinctrldev_list_mutex);
+ list_add_tail(&pctldev->node, &pinctrldev_list);
+ mutex_unlock(&pinctrldev_list_mutex);
+
+ pinctrl_init_device_debugfs(pctldev);
+
+ return 0;
+}
+
+/**
+ * pinctrl_register() - register a pin controller device
+ * @pctldesc: descriptor for this pin controller
+ * @dev: parent device for this pin controller
+ * @driver_data: private pin controller data for this pin controller
+ *
+ * Note that pinctrl_register() is known to have problems as the pin
+ * controller driver functions are called before the driver has a
+ * struct pinctrl_dev handle. To avoid issues later on, please use the
+ * new pinctrl_register_and_init() below instead.
+ */
+struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
+ struct device *dev, void *driver_data)
+{
+ struct pinctrl_dev *pctldev;
+ int error;
+
+ pctldev = pinctrl_init_controller(pctldesc, dev, driver_data);
+ if (IS_ERR(pctldev))
+ return pctldev;
+
+ error = pinctrl_create_and_start(pctldev);
+ if (error) {
+ mutex_destroy(&pctldev->mutex);
+ kfree(pctldev);
+
+ return ERR_PTR(error);
+ }
+
+ return pctldev;
+
+}
EXPORT_SYMBOL_GPL(pinctrl_register);

+int pinctrl_register_and_init(struct pinctrl_desc *pctldesc,
+ struct device *dev, void *driver_data,
+ struct pinctrl_dev **pctldev)
+{
+ struct pinctrl_dev *p;
+ int error;
+
+ p = pinctrl_init_controller(pctldesc, dev, driver_data);
+ if (IS_ERR(p))
+ return PTR_ERR(p);
+
+ /*
+ * We have pinctrl_start() call functions in the pin controller
+ * driver with create_pinctrl() for at least dt_node_to_map(). So
+ * let's make sure pctldev is properly initialized for the
+ * pin controller driver before we do anything.
+ */
+ *pctldev = p;
+
+ error = pinctrl_create_and_start(p);
+ if (error) {
+ mutex_destroy(&p->mutex);
+ kfree(p);
+ *pctldev = NULL;
+
+ return error;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pinctrl_register_and_init);
+
/**
* pinctrl_unregister() - unregister pinmux
* @pctldev: pin controller to unregister
@@ -2052,7 +2094,6 @@ void pinctrl_unregister(struct pinctrl_dev *pctldev)
if (pctldev == NULL)
return;

- cancel_delayed_work_sync(&pctldev->late_init);
mutex_lock(&pctldev->mutex);
pinctrl_remove_device_debugfs(pctldev);
mutex_unlock(&pctldev->mutex);
@@ -2134,6 +2175,42 @@ struct pinctrl_dev *devm_pinctrl_register(struct device *dev,
EXPORT_SYMBOL_GPL(devm_pinctrl_register);

/**
+ * devm_pinctrl_register_and_init() - Resource managed pinctrl register and init
+ * @dev: parent device for this pin controller
+ * @pctldesc: descriptor for this pin controller
+ * @driver_data: private pin controller data for this pin controller
+ *
+ * Returns an error pointer if pincontrol register failed. Otherwise
+ * it returns valid pinctrl handle.
+ *
+ * The pinctrl device will be automatically released when the device is unbound.
+ */
+int devm_pinctrl_register_and_init(struct device *dev,
+ struct pinctrl_desc *pctldesc,
+ void *driver_data,
+ struct pinctrl_dev **pctldev)
+{
+ struct pinctrl_dev **ptr;
+ int error;
+
+ ptr = devres_alloc(devm_pinctrl_dev_release, sizeof(*ptr), GFP_KERNEL);
+ if (!ptr)
+ return -ENOMEM;
+
+ error = pinctrl_register_and_init(pctldesc, dev, driver_data, pctldev);
+ if (error) {
+ devres_free(ptr);
+ return error;
+ }
+
+ *ptr = *pctldev;
+ devres_add(dev, ptr);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(devm_pinctrl_register_and_init);
+
+/**
* devm_pinctrl_unregister() - Resource managed version of pinctrl_unregister().
* @dev: device for which which resource was allocated
* @pctldev: the pinctrl device to unregister.
diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h
--- a/drivers/pinctrl/core.h
+++ b/drivers/pinctrl/core.h
@@ -37,7 +37,6 @@ struct pinctrl_gpio_range;
* @p: result of pinctrl_get() for this device
* @hog_default: default state for pins hogged by this device
* @hog_sleep: sleep state for pins hogged by this device
- * @late_init: delayed work for pin controller to finish registration
* @mutex: mutex taken on each pin controller specific action
* @device_root: debugfs root for this device
*/
@@ -60,7 +59,6 @@ struct pinctrl_dev {
struct pinctrl *p;
struct pinctrl_state *hog_default;
struct pinctrl_state *hog_sleep;
- struct delayed_work late_init;
struct mutex mutex;
#ifdef CONFIG_DEBUG_FS
struct dentry *device_root;
diff --git a/drivers/pinctrl/freescale/pinctrl-imx.c b/drivers/pinctrl/freescale/pinctrl-imx.c
--- a/drivers/pinctrl/freescale/pinctrl-imx.c
+++ b/drivers/pinctrl/freescale/pinctrl-imx.c
@@ -774,11 +774,11 @@ int imx_pinctrl_probe(struct platform_device *pdev,
ipctl->info = info;
ipctl->dev = info->dev;
platform_set_drvdata(pdev, ipctl);
- ipctl->pctl = devm_pinctrl_register(&pdev->dev,
- imx_pinctrl_desc, ipctl);
- if (IS_ERR(ipctl->pctl)) {
+ ret = devm_pinctrl_register_and_init(&pdev->dev,
+ imx_pinctrl_desc, ipctl,
+ &ipctl->pctl);
+ if (ret) {
dev_err(&pdev->dev, "could not register IMX pinctrl driver\n");
- ret = PTR_ERR(ipctl->pctl);
goto free;
}

diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c
--- a/drivers/pinctrl/pinctrl-single.c
+++ b/drivers/pinctrl/pinctrl-single.c
@@ -1747,10 +1747,9 @@ static int pcs_probe(struct platform_device *pdev)
if (ret < 0)
goto free;

- pcs->pctl = pinctrl_register(&pcs->desc, pcs->dev, pcs);
- if (IS_ERR(pcs->pctl)) {
+ ret = pinctrl_register_and_init(&pcs->desc, pcs->dev, pcs, &pcs->pctl);
+ if (ret) {
dev_err(pcs->dev, "could not register single pinctrl driver\n");
- ret = PTR_ERR(pcs->pctl);
goto free;
}

diff --git a/drivers/pinctrl/sh-pfc/pinctrl.c b/drivers/pinctrl/sh-pfc/pinctrl.c
--- a/drivers/pinctrl/sh-pfc/pinctrl.c
+++ b/drivers/pinctrl/sh-pfc/pinctrl.c
@@ -816,6 +816,6 @@ int sh_pfc_register_pinctrl(struct sh_pfc *pfc)
pmx->pctl_desc.pins = pmx->pins;
pmx->pctl_desc.npins = pfc->info->nr_pins;

- pmx->pctl = devm_pinctrl_register(pfc->dev, &pmx->pctl_desc, pmx);
- return PTR_ERR_OR_ZERO(pmx->pctl);
+ return devm_pinctrl_register_and_init(pfc->dev, &pmx->pctl_desc, pmx,
+ &pmx->pctl);
}
diff --git a/drivers/pinctrl/ti/pinctrl-ti-iodelay.c b/drivers/pinctrl/ti/pinctrl-ti-iodelay.c
--- a/drivers/pinctrl/ti/pinctrl-ti-iodelay.c
+++ b/drivers/pinctrl/ti/pinctrl-ti-iodelay.c
@@ -891,10 +891,9 @@ static int ti_iodelay_probe(struct platform_device *pdev)
iod->desc.name = dev_name(dev);
iod->desc.owner = THIS_MODULE;

- iod->pctl = pinctrl_register(&iod->desc, dev, iod);
- if (!iod->pctl) {
+ ret = pinctrl_register_and_init(&iod->desc, dev, iod, &iod->pctl);
+ if (ret) {
dev_err(dev, "Failed to register pinctrl\n");
- ret = -ENODEV;
goto exit_out;
}

diff --git a/include/linux/pinctrl/pinctrl.h b/include/linux/pinctrl/pinctrl.h
--- a/include/linux/pinctrl/pinctrl.h
+++ b/include/linux/pinctrl/pinctrl.h
@@ -141,12 +141,27 @@ struct pinctrl_desc {
};

/* External interface to pin controller */
+
+extern int pinctrl_register_and_init(struct pinctrl_desc *pctldesc,
+ struct device *dev, void *driver_data,
+ struct pinctrl_dev **pctldev);
+
+/* Please use pinctrl_register_and_init() instead */
extern struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
struct device *dev, void *driver_data);
+
extern void pinctrl_unregister(struct pinctrl_dev *pctldev);
+
+extern int devm_pinctrl_register_and_init(struct device *dev,
+ struct pinctrl_desc *pctldesc,
+ void *driver_data,
+ struct pinctrl_dev **pctldev);
+
+/* Please use devm_pinctrl_register_and_init() instead */
extern struct pinctrl_dev *devm_pinctrl_register(struct device *dev,
struct pinctrl_desc *pctldesc,
void *driver_data);
+
extern void devm_pinctrl_unregister(struct device *dev,
struct pinctrl_dev *pctldev);

--
2.11.0
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