From 8ae0d7e8a918e9603748abe9b31984fc5d96abb3 Mon Sep 17 00:00:00 2001
From: Mark Brown <broonie@opensource.wolfsonmicro.com>
Date: Wed, 26 Oct 2011 10:34:22 +0200
Subject: regmap: Track if the register cache is dirty and suppress unneeded
 syncs

Allow drivers to optimise out the register cache sync if they didn't need
to do one. If the hardware is desynced from the register cache (by power
loss for example) then the driver should call regcache_mark_dirty() to
let the core know about this.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 drivers/base/regmap/internal.h |  1 +
 drivers/base/regmap/regcache.c | 19 +++++++++++++++++++
 drivers/base/regmap/regmap.c   |  4 +++-
 3 files changed, 23 insertions(+), 1 deletion(-)

(limited to 'drivers/base/regmap')

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 348ff02eb93..6483e0bda0c 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -74,6 +74,7 @@ struct regmap {
 	struct reg_default *reg_defaults;
 	const void *reg_defaults_raw;
 	void *cache;
+	bool cache_dirty;
 };
 
 struct regcache_ops {
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 666f6f5011d..6ab9f0384d8 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -241,6 +241,8 @@ int regcache_sync(struct regmap *map)
 		map->cache_ops->name);
 	name = map->cache_ops->name;
 	trace_regcache_sync(map->dev, name, "start");
+	if (!map->cache_dirty)
+		goto out;
 	if (map->cache_ops->sync) {
 		ret = map->cache_ops->sync(map);
 	} else {
@@ -290,6 +292,23 @@ void regcache_cache_only(struct regmap *map, bool enable)
 }
 EXPORT_SYMBOL_GPL(regcache_cache_only);
 
+/**
+ * regcache_mark_dirty: Mark the register cache as dirty
+ *
+ * @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.
+ */
+void regcache_mark_dirty(struct regmap *map)
+{
+	mutex_lock(&map->lock);
+	map->cache_dirty = true;
+	mutex_unlock(&map->lock);
+}
+EXPORT_SYMBOL_GPL(regcache_mark_dirty);
+
 /**
  * regcache_cache_bypass: Put a register map into cache bypass mode
  *
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index bf441db1ee9..3aca18dbf36 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -306,8 +306,10 @@ int _regmap_write(struct regmap *map, unsigned int reg,
 		ret = regcache_write(map, reg, val);
 		if (ret != 0)
 			return ret;
-		if (map->cache_only)
+		if (map->cache_only) {
+			map->cache_dirty = true;
 			return 0;
+		}
 	}
 
 	trace_regmap_reg_write(map->dev, reg, val);
-- 
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