[PATCH] pinctrl: Enforce device links

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

Instead of opt-in device links, enforce it across the board.
Everyone probably needs this anyway, lest runtime[_pm] suspend
order will be haphazard.

Cc: Benjamin GAIGNARD <benjamin.gaignard@xxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
ChangeLog v1->v2:
- Create links per setting (since settings can be on different
  pin controllers) when adding a setting to a pin control handle,
  instead of doing this when activating the state.
- Store the link inside the setting.
- Delete the link when we free up the setting.

Benjamin: it would be GREAT if you could test this!
---
 drivers/pinctrl/core.c                | 35 +++++++++++++++++----------
 drivers/pinctrl/core.h                |  3 +++
 drivers/pinctrl/pinctrl-stmfx.c       |  1 -
 drivers/pinctrl/stm32/pinctrl-stm32.c |  1 -
 include/linux/pinctrl/pinctrl.h       |  5 ----
 5 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 2bbd8ee93507..89ac42a145f2 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -1000,6 +1000,26 @@ static int add_setting(struct pinctrl *p, struct pinctrl_dev *pctldev,
 
 	list_add_tail(&setting->node, &state->settings);
 
+	/*
+	 * Set up a device link for power management.
+	 * Do not link hogs (circular dependency)
+	 * Do not create more than one link per pinctrl.
+	 */
+	if (p->dev != setting->pctldev->dev) {
+		/*
+		 * Create a device link to the consumer such that
+		 * it will enforce that runtime PM suspend/resume
+		 * is done first on consumers before we get to
+		 * the pin controller itself. As some devices get
+		 * their pin control state even before probe() it is
+		 * important to use DL_FLAG_AUTOREMOVE_CONSUMER.
+		 */
+		setting->dl = device_link_add(p->dev,
+					      setting->pctldev->dev,
+					      DL_FLAG_PM_RUNTIME |
+					      DL_FLAG_AUTOREMOVE_CONSUMER);
+	}
+
 	return 0;
 }
 
@@ -1135,6 +1155,8 @@ EXPORT_SYMBOL_GPL(pinctrl_get);
 static void pinctrl_free_setting(bool disable_setting,
 				 struct pinctrl_setting *setting)
 {
+	if (setting->dl)
+		device_link_del(setting->dl);
 	switch (setting->type) {
 	case PIN_MAP_TYPE_MUX_GROUP:
 		if (disable_setting)
@@ -1220,15 +1242,6 @@ struct pinctrl_state *pinctrl_lookup_state(struct pinctrl *p,
 }
 EXPORT_SYMBOL_GPL(pinctrl_lookup_state);
 
-static void pinctrl_link_add(struct pinctrl_dev *pctldev,
-			     struct device *consumer)
-{
-	if (pctldev->desc->link_consumers)
-		device_link_add(consumer, pctldev->dev,
-				DL_FLAG_PM_RUNTIME |
-				DL_FLAG_AUTOREMOVE_CONSUMER);
-}
-
 /**
  * pinctrl_commit_state() - select/activate/program a pinctrl state to HW
  * @p: the pinctrl handle for the device that requests configuration
@@ -1274,10 +1287,6 @@ static int pinctrl_commit_state(struct pinctrl *p, struct pinctrl_state *state)
 		if (ret < 0) {
 			goto unapply_new_state;
 		}
-
-		/* Do not link hogs (circular dependency) */
-		if (p != setting->pctldev->p)
-			pinctrl_link_add(setting->pctldev, p->dev);
 	}
 
 	p->state = state;
diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h
index 7f34167a0405..4073a1e4dde1 100644
--- a/drivers/pinctrl/core.h
+++ b/drivers/pinctrl/core.h
@@ -11,6 +11,7 @@
 #include <linux/kref.h>
 #include <linux/mutex.h>
 #include <linux/radix-tree.h>
+#include <linux/device.h>
 #include <linux/pinctrl/pinconf.h>
 #include <linux/pinctrl/machine.h>
 
@@ -126,6 +127,7 @@ struct pinctrl_setting_configs {
  * @pctldev: pin control device handling to be programmed. Not used for
  *   PIN_MAP_TYPE_DUMMY_STATE.
  * @dev_name: the name of the device using this state
+ * @dl: device link for power management
  * @data: Data specific to the setting type
  */
 struct pinctrl_setting {
@@ -133,6 +135,7 @@ struct pinctrl_setting {
 	enum pinctrl_map_type type;
 	struct pinctrl_dev *pctldev;
 	const char *dev_name;
+	struct device_link *dl;
 	union {
 		struct pinctrl_setting_mux mux;
 		struct pinctrl_setting_configs configs;
diff --git a/drivers/pinctrl/pinctrl-stmfx.c b/drivers/pinctrl/pinctrl-stmfx.c
index 16723797fa7c..4306b8444188 100644
--- a/drivers/pinctrl/pinctrl-stmfx.c
+++ b/drivers/pinctrl/pinctrl-stmfx.c
@@ -638,7 +638,6 @@ static int stmfx_pinctrl_probe(struct platform_device *pdev)
 	pctl->pctl_desc.pins = stmfx_pins;
 	pctl->pctl_desc.npins = ARRAY_SIZE(stmfx_pins);
 	pctl->pctl_desc.owner = THIS_MODULE;
-	pctl->pctl_desc.link_consumers = true;
 
 	ret = devm_pinctrl_register_and_init(pctl->dev, &pctl->pctl_desc,
 					     pctl, &pctl->pctl_dev);
diff --git a/drivers/pinctrl/stm32/pinctrl-stm32.c b/drivers/pinctrl/stm32/pinctrl-stm32.c
index 2d5e0435af0a..ec59a58600ce 100644
--- a/drivers/pinctrl/stm32/pinctrl-stm32.c
+++ b/drivers/pinctrl/stm32/pinctrl-stm32.c
@@ -1439,7 +1439,6 @@ int stm32_pctl_probe(struct platform_device *pdev)
 	pctl->pctl_desc.owner = THIS_MODULE;
 	pctl->pctl_desc.pins = pins;
 	pctl->pctl_desc.npins = pctl->npins;
-	pctl->pctl_desc.link_consumers = true;
 	pctl->pctl_desc.confops = &stm32_pconf_ops;
 	pctl->pctl_desc.pctlops = &stm32_pctrl_ops;
 	pctl->pctl_desc.pmxops = &stm32_pmx_ops;
diff --git a/include/linux/pinctrl/pinctrl.h b/include/linux/pinctrl/pinctrl.h
index 7ce23450a1cb..c6159f041f4e 100644
--- a/include/linux/pinctrl/pinctrl.h
+++ b/include/linux/pinctrl/pinctrl.h
@@ -122,10 +122,6 @@ struct pinctrl_ops {
  *	the hardware description
  * @custom_conf_items: Information how to print @params in debugfs, must be
  *	the same size as the @custom_params, i.e. @num_custom_params
- * @link_consumers: If true create a device link between pinctrl and its
- *	consumers (i.e. the devices requesting pin control states). This is
- *	sometimes necessary to ascertain the right suspend/resume order for
- *	example.
  */
 struct pinctrl_desc {
 	const char *name;
@@ -140,7 +136,6 @@ struct pinctrl_desc {
 	const struct pinconf_generic_params *custom_params;
 	const struct pin_config_item *custom_conf_items;
 #endif
-	bool link_consumers;
 };
 
 /* External interface to pin controller */
-- 
2.23.0