ASoC: STA32x: Preserve reserved register bits

Chip documentation explicitly requires that the reset values
of reserved register bits are left untouched.  It is possible
there are differences between STA326 and STA328 or future
chip revisions in these bits, and clobbering them might
cause malfunction.

Signed-off-by: Johannes Stezenbach <js@sig21.net>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

diff --git a/sound/soc/codecs/sta32x.c b/sound/soc/codecs/sta32x.c
index 9bf944ca43a1f58cdb70cba3e60e05e8e0b68d68..409d89d1f34c26fb44b58d979256541d798a5dc1 100644 (file)
--- a/sound/soc/codecs/sta32x.c
+++ b/sound/soc/codecs/sta32x.c
@@ -756,6 +756,22 @@ static int sta32x_probe(struct snd_soc_codec *codec)
        for (i = 0; i < STA32X_REGISTER_COUNT; i++)
                snd_soc_cache_write(codec, i, sta32x_regs[i]);
 
+       /* preserve reset values of reserved register bits */
+       snd_soc_cache_write(codec, STA32X_CONFC,
+                           codec->hw_read(codec, STA32X_CONFC));
+       snd_soc_cache_write(codec, STA32X_CONFE,
+                           codec->hw_read(codec, STA32X_CONFE));
+       snd_soc_cache_write(codec, STA32X_CONFF,
+                           codec->hw_read(codec, STA32X_CONFF));
+       snd_soc_cache_write(codec, STA32X_MMUTE,
+                           codec->hw_read(codec, STA32X_MMUTE));
+       snd_soc_cache_write(codec, STA32X_AUTO1,
+                           codec->hw_read(codec, STA32X_AUTO1));
+       snd_soc_cache_write(codec, STA32X_AUTO3,
+                           codec->hw_read(codec, STA32X_AUTO3));
+       snd_soc_cache_write(codec, STA32X_C3CFG,
+                           codec->hw_read(codec, STA32X_C3CFG));
+
        /* FIXME enable thermal warning adjustment and recovery  */
        snd_soc_update_bits(codec, STA32X_CONFA,
                            STA32X_CONFA_TWAB | STA32X_CONFA_TWRB, 0);