diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index a13587b5c2be..b2b2849fc6d3 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -131,7 +131,10 @@ struct regmap {
 	struct reg_default *reg_defaults;
 	const void *reg_defaults_raw;
 	void *cache;
+	/* if set, the cache contains newer data than the HW */
 	u32 cache_dirty;
+	/* if set, the HW registers are known to match map->reg_defaults */
+	bool no_sync_defaults;
 
 	struct reg_default *patch;
 	int patch_regs;
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index c58493eaf050..b9862d741a56 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -254,6 +254,10 @@ static bool regcache_reg_needs_sync(struct regmap *map, unsigned int reg,
 {
 	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)
@@ -352,6 +356,7 @@ int regcache_sync(struct regmap *map)
 	/* 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);
@@ -407,6 +412,7 @@ int regcache_sync_region(struct regmap *map, unsigned int min,
 	/* 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);
@@ -471,18 +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);