regmap: fix bogus error on regcache_sync success

stable inclusion
from stable-v6.6.7
commit 78c8fc333253077c5276bc3b4207818d45410acb
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8SSQ4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=78c8fc333253077c5276bc3b4207818d45410acb



--------------------------------

commit fea88064445a59584460f7f67d102b6e5fc1ca1d upstream.

Since commit 0ec7731655de ("regmap: Ensure range selector registers
are updated after cache sync") opening pcm512x based soundcards fail
with EINVAL and dmesg shows sync cache and pm_runtime_get errors:

[  228.794676] pcm512x 1-004c: Failed to sync cache: -22
[  228.794740] pcm512x 1-004c: ASoC: error at snd_soc_pcm_component_pm_runtime_get on pcm512x.1-004c: -22

This is caused by the cache check result leaking out into the
regcache_sync return value.

Fix this by making the check local-only, as the comment above the
regcache_read call states a non-zero return value means there's
nothing to do so the return value should not be altered.

Fixes: 0ec7731655de ("regmap: Ensure range selector registers are updated after cache sync")
Cc: stable@vger.kernel.org
Signed-off-by: Matthias Reichl <hias@horus.com>
Link: https://lore.kernel.org/r/20231203222216.96547-1-hias@horus.com


Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>