ASoC: Implement new DC servo readback mode for late WM8994 revisions

Later WM8994 devices implement a new DC servo readback mode with the
register used to access the offset moved to register 0x59. Implement
support for this and enable it on the appropriate devices.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/sound/soc/codecs/wm8994.c b/sound/soc/codecs/wm8994.c
index 09e680ae88b2..c0956899d5b5 100644
--- a/sound/soc/codecs/wm8994.c
+++ b/sound/soc/codecs/wm8994.c
@@ -107,6 +107,7 @@ static int wm8994_volatile(struct snd_soc_codec *codec, unsigned int reg)
         case WM8994_LDO_2:
         case WM8958_DSP2_EXECCONTROL:
         case WM8958_MIC_DETECT_3:
+        case WM8994_DC_SERVO_4E:
                 return 1;
         default:
                 return 0;
@@ -2978,7 +2979,7 @@ static int wm8994_codec_probe(struct snd_soc_codec *codec)
                         wm8994->hubs.series_startup = 1;
                         break;
                 default:
-                        wm8994->hubs.dcs_readback_mode = 1;
+                        wm8994->hubs.dcs_readback_mode = 2;
                         break;
                 }