[PATCH] regmap: maple: Don't sync read-only registers

[Takashi Iwai]

regcache_maple_sync() tries to sync all cached values no matter
whether it's writable or not.  OTOH, regache_sync_val() does care the
wrtability and returns -EIO for a read-only register.  This results in
an error message like:
  snd_hda_codec_realtek hdaudioC0D0: Unable to sync register 0x2f0009. -5
and the sync loop is aborted incompletely.

This patch adds the writable register check in the loop for addressing
the bug.

Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache")
Link: https://lore.kernel.org/r/877cs7g6f1.wl-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
 drivers/base/regmap/regcache-maple.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/regmap/regcache-maple.c b/drivers/base/regmap/regcache-maple.c
index c2e3a0f6c218..d2dad32dd399 100644
--- a/drivers/base/regmap/regcache-maple.c
+++ b/drivers/base/regmap/regcache-maple.c
@@ -203,6 +203,8 @@ static int regcache_maple_sync(struct regmap *map, unsigned int min,
 
 	mas_for_each(&mas, entry, max) {
 		for (r = max(mas.index, lmin); r <= min(mas.last, lmax); r++) {
+			if (!regmap_writeable(map, r))
+				continue;
 			mas_pause(&mas);
 			rcu_read_unlock();
 			ret = regcache_sync_val(map, r, entry[r - mas.index]);
-- 
2.35.3