From 518e26f11af2fe4f5bebf9a0351595d508c7077f Mon Sep 17 00:00:00 2001
From: Haibo Chen <haibo.chen@nxp.com>
Date: Wed, 31 Aug 2022 18:37:35 +0800
Subject: [PATCH] gpio: pca953x: Add mutex_lock for regcache sync in PM
Git-commit: 518e26f11af2fe4f5bebf9a0351595d508c7077f
Patch-mainline: v6.0-rc4
References: git-fixes

The regcache sync will set the cache_bypass = true, at that
time, when there is regmap write operation, it will bypass
the regmap cache, then the regcache sync will write back the
value from cache to register, which is not as our expectation.

Though regmap already use its internal lock to avoid such issue,
but this driver force disable the regmap internal lock in its
regmap config: disable_locking = true

To avoid this issue, use the driver's own lock to do the protect
in system PM.

Fixes: b76574300504 ("gpio: pca953x: Restore registers after suspend/resume cycle")
Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpio/gpio-pca953x.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index ecd7d169470b..2925f4d8cef3 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -1175,7 +1175,9 @@ static int pca953x_suspend(struct device *dev)
 {
 	struct pca953x_chip *chip = dev_get_drvdata(dev);
 
+	mutex_lock(&chip->i2c_lock);
 	regcache_cache_only(chip->regmap, true);
+	mutex_unlock(&chip->i2c_lock);
 
 	if (atomic_read(&chip->wakeup_path))
 		device_set_wakeup_path(dev);
@@ -1198,13 +1200,17 @@ static int pca953x_resume(struct device *dev)
 		}
 	}
 
+	mutex_lock(&chip->i2c_lock);
 	regcache_cache_only(chip->regmap, false);
 	regcache_mark_dirty(chip->regmap);
 	ret = pca953x_regcache_sync(dev);
-	if (ret)
+	if (ret) {
+		mutex_unlock(&chip->i2c_lock);
 		return ret;
+	}
 
 	ret = regcache_sync(chip->regmap);
+	mutex_unlock(&chip->i2c_lock);
 	if (ret) {
 		dev_err(dev, "Failed to restore register map: %d\n", ret);
 		return ret;
-- 
2.35.3