[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-sound
Subject:    AC97 Mic Boost Bit
From:       Dennis Newbold <dennisn () pe ! net>
Date:       2003-12-05 0:36:33
[Download RAW message or body]

Dear Kernel developers,

     Please ignore the incorrect patch file sent in my previous email,
and refer to the attached patch file instead.  All other comments in
my previous email still apply.  Thanks again.

Dennis Newbold
dennisn@pe.net

---------------------------------------------
|                                           |
|     The way to be happy is to be good     |
|                                           |
---------------------------------------------

["ac97_codec_patch2" (TEXT/PLAIN)]

--- ac97_codec.c	Thu Dec 04 15:53:12 2003

+++ linux-2.4.23/drivers/sound/ac97_codec.c	Thu Dec 04 16:30:08 2003

@@ -30,6 +30,9 @@

  **************************************************************************

  *

  * History

+ * Dec 04, 2003 Dennis Newbold <dennisn@pe.net>

+ *   Added logic to use the MICBOOST bit when writing or reading the

+ *   SOUND_MIXER_MIC channel.

  * May 02, 2003 Liam Girdwood <liam.girdwood@wolfsonmicro.com>

  *	Removed non existant WM9700

  *	Added support for WM9705, WM9708, WM9709, WM9710, WM9711

@@ -240,6 +243,26 @@

 	{-1,0}

 };

 

+/* Note that scale for SOUND_MIXER_MIC is set to 46 rather than 32.  This is

+ * to include the lower volume DB values that do not use the AC97_MICBOOST

+ * bit.  There is a small glitch in the scaling in that the last value to use

+ * the boost bit is 31, which translates to -14.5 dB, and the next lower value,

+ * which does not use the boost bit is 32, which is converted to 18, which

+ * translates to -15 dB, a difference of only 0.5 dB.  All other gain values

+ *  differ by 1.5 dB.  This is considered acceptable because it happens only

+ *  at an extremely low volume, which most users will not be interested in.

+ *  -dln- */

+

+/* MIC_NATURAL_SCALE is the no. of different gain settings that will fit in

+ * the MIC Volume Gain Register.  Computed gain values which fall within this

+ * range operate with the AC97_MICBOOST bit enabled.  Computed values outside

+ * of this range are forced back into this range, but with the AC97_MICBOOST

+ * bit turned off.  This allows access to the very low dB range scale of the

+ * AC97 codec, which cannot be accessed with the MICBOOST bit enabled. -dln-

+ */

+

+#define MIC_NATURAL_SCALE    (32)

+

 /* table to scale scale from OSS mixer value to AC97 mixer register value */	

 static struct ac97_mixer_hw {

 	unsigned char offset;

@@ -251,7 +274,7 @@

 	[SOUND_MIXER_PCM]	=	{AC97_PCMOUT_VOL,	32},

 	[SOUND_MIXER_SPEAKER]	=	{AC97_PCBEEP_VOL,	16},

 	[SOUND_MIXER_LINE]	=	{AC97_LINEIN_VOL,	32},

-	[SOUND_MIXER_MIC]	=	{AC97_MIC_VOL,		32},

+	[SOUND_MIXER_MIC]	=	{AC97_MIC_VOL,		46},

 	[SOUND_MIXER_CD]	=	{AC97_CD_VOL,		32},

 	[SOUND_MIXER_ALTPCM]	=	{AC97_HEADPHONE_VOL,	64},

 	[SOUND_MIXER_IGAIN]	=	{AC97_RECORD_GAIN,	16},

@@ -302,7 +325,7 @@

    about that given mixer, and should be holding a spinlock for the card */

 static int ac97_read_mixer(struct ac97_codec *codec, int oss_channel) 

 {

-	u16 val;

+	u16 val, t;

 	int ret = 0;

 	int scale;

 	struct ac97_mixer_hw *mh = &ac97_hw[oss_channel];

@@ -340,7 +363,10 @@

 		scale = (1 << codec->bit_resolution);

 		ret = 100 - (((val & 0x1f) * 100) / scale);

 	} else if (oss_channel == SOUND_MIXER_MIC) {

-		ret = 100 - (((val & 0x1f) * 100) / mh->scale);

+		t = val & (MIC_NATURAL_SCALE - 1);

+		if (!(val & AC97_MICBOOST))

+			t += (mh->scale - MIC_NATURAL_SCALE);

+		ret = 100 - ((t * 100) / mh->scale-1);

 		/*  the low bit is optional in the tone sliders and masking

 		    it lets us avoid the 0xf 'bypass'.. */

 	} else if (oss_channel == SOUND_MIXER_BASS) {

@@ -427,7 +453,7 @@

 		left = ((100 - left) * mh->scale) / 100;

 		if (left >= mh->scale)

 			left = mh->scale-1;

-		val = left;

+	val = left;

 	} else if (oss_channel == SOUND_MIXER_PHONEOUT) {

 		scale = (1 << codec->bit_resolution);

 		left = ((100 - left) * scale) / 100;

@@ -436,13 +462,17 @@

 		val = left;

 	} else if (oss_channel == SOUND_MIXER_MIC) {

 		val = codec->codec_read(codec , mh->offset) & ~0x801f;

-		left = ((100 - left) * mh->scale) / 100;

+		left = ((100 - left) * mh->scale-1) / 100;

 		if (left >= mh->scale)

-			left = mh->scale-1;

+			left = mh->scale-1

+		if (left < MIC_NATURAL_SCALE)

+			left |= AC97_MICBOOST;

+		else

+			left -= (mh->scale - MIC_NATURAL_SCALE);

 		val |= left;

 		/*  the low bit is optional in the tone sliders and masking

 		    it lets us avoid the 0xf 'bypass'.. */

-	}

+	

 #ifdef DEBUG

 	printk(" 0x%04x", val);

 #endif


-
To unsubscribe from this list: send the line "unsubscribe linux-sound" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[prev in list] [next in list] [prev in thread] [next in thread]