It may happen that a device needs to force applying a state, e.g:
because it only defines one state of pin states (default) but loses
power/register contents when entering low power modes. Add a
pinctrl_dev::flags bitmask to help describe future quirks and define
PINCTRL_FLG_FORCE_STATE as such a settable flag.

Signed-off-by: Florian Fainelli <f.faine...@gmail.com>
---
 drivers/pinctrl/core.c | 15 +++++++++++++++
 drivers/pinctrl/core.h |  4 ++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 56fbe4c3e800..c450a97de88f 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -1197,11 +1197,26 @@ int pinctrl_select_state(struct pinctrl *p, struct 
pinctrl_state *state)
 {
        struct pinctrl_setting *setting, *setting2;
        struct pinctrl_state *old_state = p->state;
+       bool force = false;
        int ret;
 
        if (p->state == state)
                return 0;
 
+       if (p->state) {
+               list_for_each_entry(setting, &p->state->settings, node) {
+                       if (setting->pctldev->flags & PINCTRL_FLG_FORCE_STATE)
+                               force = true;
+               }
+       }
+
+       /* Some controllers may want to force this operation when they define
+        * only one set of functions and lose power state, e.g: pinctrl-single
+        * with its pinctrl-single,low-power-state-loss property.
+        */
+       if (p->state == state && !force)
+               return 0;
+
        if (p->state) {
                /*
                 * For each pinmux setting in the old state, forget SW's record
diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h
index 7880c3adc450..5fbf4dd1fa76 100644
--- a/drivers/pinctrl/core.h
+++ b/drivers/pinctrl/core.h
@@ -39,6 +39,7 @@ struct pinctrl_gpio_range;
  * @hog_sleep: sleep state for pins hogged by this device
  * @mutex: mutex taken on each pin controller specific action
  * @device_root: debugfs root for this device
+ * @flags: feature/quirk flags
  */
 struct pinctrl_dev {
        struct list_head node;
@@ -63,8 +64,11 @@ struct pinctrl_dev {
 #ifdef CONFIG_DEBUG_FS
        struct dentry *device_root;
 #endif
+       unsigned long flags;
 };
 
+#define PINCTRL_FLG_FORCE_STATE        (1 << 0)
+
 /**
  * struct pinctrl - per-device pin control state holder
  * @node: global list node
-- 
2.14.1

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