regmap: Skip read-only registers in regcache_sync()

regcache_sync() spews warnings when a value was cached for a read-only
register as it tries to write all registers no matter whether they are
writable or not.  This patch adds regmap_wrtieable() checks for
avoiding it in regcache_sync_block_single() and regcache_block_raw().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index f373c35f9e1d..da84f544c544 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -608,7 +608,8 @@ static int regcache_sync_block_single(struct regmap *map, void *block,
         for (i = start; i < end; i++) {
                 regtmp = block_base + (i * map->reg_stride);
 
-                if (!regcache_reg_present(cache_present, i))
+                if (!regcache_reg_present(cache_present, i) ||
+                    !regmap_writeable(map, regtmp))
                         continue;
 
                 val = regcache_get_val(map, block, i);
@@ -677,7 +678,8 @@ static int regcache_sync_block_raw(struct regmap *map, void *block,
         for (i = start; i < end; i++) {
                 regtmp = block_base + (i * map->reg_stride);
 
-                if (!regcache_reg_present(cache_present, i)) {
+                if (!regcache_reg_present(cache_present, i) ||
+                    !regmap_writeable(map, regtmp)) {
                         ret = regcache_sync_block_raw_flush(map, &data,
                                                             base, regtmp);
                         if (ret != 0)