From: Elaine Zhang <zhangqing@rock-chips.com>
Date: Thu, 18 Aug 2016 09:01:55 +0000 (+0800)
Subject: UPSTREAM: regmap: drop cache if the bus transfer error
X-Git-Tag: firefly_0821_release~1716
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=firefly-linux-kernel-4.4.55.git;a=commitdiff_plain;h=9f878e7885e8337953c2632e9fcc60146abca552

UPSTREAM: regmap: drop cache if the bus transfer error

regmap_write
->_regmap_raw_write
-->regcache_write first and than use map->bus->write to write i2c or spi
But if the i2c or spi transfer failed, But the cache is updated, So if I use
regmap_read will get the cache data which is not the real register value.

Change-Id: Iae06edf8a2a50d2561d351a8398bd3140904630c
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
(cherry picked from
 git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git
 commit 815806e39bf6f7e7b34875d4a9609dbe76661782)
---

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 4ac63c0e50c7..bb216c9d3c09 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1372,6 +1372,8 @@ int _regmap_raw_write(struct regmap *map, unsigned int reg,
 		ret = map->bus->write(map->bus_context, buf, len);
 
 		kfree(buf);
+	} else if (ret != 0 && !map->cache_bypass && map->format.parse_val) {
+		regcache_drop_region(map, reg, reg + 1);
 	}
 
 	trace_regmap_hw_write_done(map, reg, val_len / map->format.val_bytes);