ASoC: wm8994: VMID management improvements

Raise the ramp time to 50ms to cover corner cases, use the startup bias
generator, explicitly reset the ramp circuit when complete and reorder
things all of which should improve performance somewhat for systems that
are sensitive to noise from VMID.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/wm8994.c

@@ -778,29 +778,37 @@ static void vmid_reference(struct snd_soc_codec *codec)
 		wm8994->vmid_refcount);
 
 	if (wm8994->vmid_refcount == 1) {
+		snd_soc_update_bits(codec, WM8994_ANTIPOP_1,
+				    WM8994_LINEOUT_VMID_BUF_ENA |
+				    WM8994_LINEOUT1_DISCH |
+				    WM8994_LINEOUT2_DISCH,
+				    WM8994_LINEOUT_VMID_BUF_ENA);
+
 		/* Startup bias, VMID ramp & buffer */
 		snd_soc_update_bits(codec, WM8994_ANTIPOP_2,
+				    WM8994_BIAS_SRC |
+				    WM8994_VMID_DISCH |
 				    WM8994_STARTUP_BIAS_ENA |
 				    WM8994_VMID_BUF_ENA |
 				    WM8994_VMID_RAMP_MASK,
+				    WM8994_BIAS_SRC |
 				    WM8994_STARTUP_BIAS_ENA |
 				    WM8994_VMID_BUF_ENA |
 				    (0x3 << WM8994_VMID_RAMP_SHIFT));
 
 		wm_hubs_vmid_ena(codec);
 
-		/* Remove discharge for line out */
-		snd_soc_update_bits(codec, WM8994_ANTIPOP_1,
-				    WM8994_LINEOUT1_DISCH |
-				    WM8994_LINEOUT2_DISCH, 0);
-
 		/* Main bias enable, VMID=2x40k */
 		snd_soc_update_bits(codec, WM8994_POWER_MANAGEMENT_1,
 				    WM8994_BIAS_ENA |
 				    WM8994_VMID_SEL_MASK,
 				    WM8994_BIAS_ENA | 0x2);
 
-		msleep(20);
+		msleep(50);
+
+		snd_soc_update_bits(codec, WM8994_ANTIPOP_2,
+				    WM8994_VMID_RAMP_MASK | WM8994_BIAS_SRC,
+				    0);
 	}
 }