1 files changed, 30 insertions, 15 deletions

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 7eb7b3b98794..b9862d741a56 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -249,6 +249,22 @@ int regcache_write(struct regmap *map,
 	return 0;
 }
 
+static bool regcache_reg_needs_sync(struct regmap *map, unsigned int reg,
+				    unsigned int val)
+{
+	int ret;
+
+	/* If we don't know the chip just got reset, then sync everything. */
+	if (!map->no_sync_defaults)
+		return true;
+
+	/* Is this the hardware default?  If so skip. */
+	ret = regcache_lookup_reg(map, reg);
+	if (ret >= 0 && val == map->reg_defaults[ret].def)
+		return false;
+	return true;
+}
+
 static int regcache_default_sync(struct regmap *map, unsigned int min,
 				 unsigned int max)
 {
@@ -266,9 +282,7 @@ static int regcache_default_sync(struct regmap *map, unsigned int min,
 		if (ret)
 			return ret;
 
-		/* Is this the hardware default?  If so skip. */
-		ret = regcache_lookup_reg(map, reg);
-		if (ret >= 0 && val == map->reg_defaults[ret].def)
+		if (!regcache_reg_needs_sync(map, reg, val))
 			continue;
 
 		map->cache_bypass = 1;
@@ -342,6 +356,7 @@ out:
 	/* Restore the bypass state */
 	map->async = false;
 	map->cache_bypass = bypass;
+	map->no_sync_defaults = false;
 	map->unlock(map->lock_arg);
 
 	regmap_async_complete(map);
@@ -397,6 +412,7 @@ out:
 	/* Restore the bypass state */
 	map->cache_bypass = bypass;
 	map->async = false;
+	map->no_sync_defaults = false;
 	map->unlock(map->lock_arg);
 
 	regmap_async_complete(map);
@@ -461,18 +477,23 @@ void regcache_cache_only(struct regmap *map, bool enable)
 EXPORT_SYMBOL_GPL(regcache_cache_only);
 
 /**
- * regcache_mark_dirty: Mark the register cache as dirty
+ * regcache_mark_dirty: Indicate that HW registers were reset to default values
  *
  * @map: map to mark
  *
- * Mark the register cache as dirty, for example due to the device
- * having been powered down for suspend.  If the cache is not marked
- * as dirty then the cache sync will be suppressed.
+ * Inform regcache that the device has been powered down or reset, so that
+ * on resume, regcache_sync() knows to write out all non-default values
+ * stored in the cache.
+ *
+ * If this function is not called, regcache_sync() will assume that
+ * the hardware state still matches the cache state, modulo any writes that
+ * happened when cache_only was true.
  */
 void regcache_mark_dirty(struct regmap *map)
 {
 	map->lock(map->lock_arg);
 	map->cache_dirty = true;
+	map->no_sync_defaults = true;
 	map->unlock(map->lock_arg);
 }
 EXPORT_SYMBOL_GPL(regcache_mark_dirty);
@@ -613,10 +634,7 @@ static int regcache_sync_block_single(struct regmap *map, void *block,
 			continue;
 
 		val = regcache_get_val(map, block, i);
-
-		/* Is this the hardware default?  If so skip. */
-		ret = regcache_lookup_reg(map, regtmp);
-		if (ret >= 0 && val == map->reg_defaults[ret].def)
+		if (!regcache_reg_needs_sync(map, regtmp, val))
 			continue;
 
 		map->cache_bypass = 1;
@@ -688,10 +706,7 @@ static int regcache_sync_block_raw(struct regmap *map, void *block,
 		}
 
 		val = regcache_get_val(map, block, i);
-
-		/* Is this the hardware default?  If so skip. */
-		ret = regcache_lookup_reg(map, regtmp);
-		if (ret >= 0 && val == map->reg_defaults[ret].def) {
+		if (!regcache_reg_needs_sync(map, regtmp, val)) {
 			ret = regcache_sync_block_raw_flush(map, &data,
 							    base, regtmp);
 			if (ret != 0)