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regmap: regcache: Don't sync read-only registers
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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 to regcache_sync_val() for
addressing the bug above.

Note that, although we may add the check in the caller side
(regcache_maple_sync()), here we put in regcache_sync_val(), so that a
similar case like this can be avoided in future.

Fixes: f033c26 ("regmap: Add maple tree based register cache")
Link: https://lore.kernel.org/r/877cs7g6f1.wl-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20230613112240.3361-1-tiwai@suse.de
Signed-off-by: Mark Brown <broonie@kernel.org>
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Takashi Iwai authored and Mark Brown committed Jun 13, 2023
1 parent 0cc6578 commit 44e4657
Showing 1 changed file with 3 additions and 0 deletions.
3 changes: 3 additions & 0 deletions drivers/base/regmap/regcache.c
Original file line number Diff line number Diff line change
Expand Up @@ -284,6 +284,9 @@ static bool regcache_reg_needs_sync(struct regmap *map, unsigned int reg,
{
int ret;

if (!regmap_writeable(map, reg))
return false;

/* If we don't know the chip just got reset, then sync everything. */
if (!map->no_sync_defaults)
return true;
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