Loud screech after reboot of 2.2.18-pre22

Hi,

I have a Sony VAIO Z505JE with ymfpci sound and built-in microphone and speaker. Everything worked fine with 2.2.17 plus ymfpci patch, but the 2.2.18-pre22 produces a loud screech starting as sound initializes and ending when startup scrips load mixer settings. This happens because of audio loop between microphone and speakers.

I found that the culprit is the change to values of array mixer_defaults[] in ac97_codec.c, that happened in 2.2.18-pre.

Currently I run the following patch:

@@ -131,7 +131,7 @@
 	{SOUND_MIXER_PCM,	0x4343},
 	{SOUND_MIXER_SPEAKER,	0x4343},
 	{SOUND_MIXER_LINE,	0x4343},
-	{SOUND_MIXER_MIC,	0x4343},
+	{SOUND_MIXER_MIC,	0x1111},	/* P3 - audio loop */
 	{SOUND_MIXER_CD,	0x4343},
 	{SOUND_MIXER_ALTPCM,	0x4343},
 	{SOUND_MIXER_IGAIN,	0x4343},

I wonder if there is a better way?

In the interests of full disclosure let me mention that YMFxxx do have internal loopbacks that may produce the same effect and that I checked to the best of my ability that those loopbacks are muted. Therefore I conclude that the loopback happens inside the AC97 (if such a thing is possible).

--Pete
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