ASoC: wm_hubs: Clamp inputs to VMID while we ramp

Reduces the amount of time taken to stabilise them.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/wm8993.h

@@ -31,6 +31,7 @@
 #define WM8993_GPIO_CTRL_1                      0x12
 #define WM8993_GPIO1                            0x13
 #define WM8993_IRQ_DEBOUNCE                     0x14
+#define WM8993_INPUTS_CLAMP_REG			0x15
 #define WM8993_GPIOCTRL_2                       0x16
 #define WM8993_GPIO_POL                         0x17
 #define WM8993_LEFT_LINE_INPUT_1_2_VOLUME       0x18
@@ -655,6 +656,14 @@
 #define WM8993_GPIO1_DB_SHIFT                        0  /* GPIO1_DB */
 #define WM8993_GPIO1_DB_WIDTH                        1  /* GPIO1_DB */
 
+/*
+ * R21 (0x15) - Inputs Clamp
+ */
+#define WM8993_INPUTS_CLAMP                     0x0040  /* INPUTS_CLAMP */
+#define WM8993_INPUTS_CLAMP_MASK                0x0040  /* INPUTS_CLAMP */
+#define WM8993_INPUTS_CLAMP_SHIFT                    7  /* INPUTS_CLAMP */
+#define WM8993_INPUTS_CLAMP_WIDTH                    1  /* INPUTS_CLAMP */
+
 /*
  * R22 (0x16) - GPIOCTRL 2
  */

sound/soc/codecs/wm_hubs.c

@@ -1040,6 +1040,12 @@ void wm_hubs_set_bias_level(struct snd_soc_codec *codec,
 	int val;
 
 	switch (level) {
+	case SND_SOC_BIAS_STANDBY:
+		/* Clamp the inputs to VMID while we ramp to charge caps */
+		snd_soc_update_bits(codec, WM8993_INPUTS_CLAMP_REG,
+				    WM8993_INPUTS_CLAMP, WM8993_INPUTS_CLAMP);
+		break;
+
 	case SND_SOC_BIAS_ON:
 		/* Turn off any unneded single ended outputs */
 		val = 0;
@@ -1067,6 +1073,10 @@ void wm_hubs_set_bias_level(struct snd_soc_codec *codec,
 		    !hubs->lineout2n_ena && !hubs->lineout2p_ena)
 			snd_soc_update_bits(codec, WM8993_ANTIPOP1,
 					    WM8993_LINEOUT_VMID_BUF_ENA, 0);
+
+		/* Remove the input clamps */
+		snd_soc_update_bits(codec, WM8993_INPUTS_CLAMP_REG,
+				    WM8993_INPUTS_CLAMP, 0);
 		break;
 
 	default: