[ALSA] [ac97 core] added AC97_SCAP_DETECT_BY_VENDOR flag

AC97 Codec Core,Intel8x0 driver
This patch adds a AC97_SCAP_DETECT_BY_VENDOR flag for Xbox. If the flag
is set, the AC97 codec is detected only by reading of a reasonable
vendor ID. It seems that Xbox has accessible only vendor/device ID
registers for reading. Also, a new xbox parameter for snd-intel8x0
has been introduced to let user force this behaviour.
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

include/sound/ac97_codec.h

@@ -355,6 +355,7 @@
 #define AC97_SCAP_SKIP_MODEM	(1<<5)	/* skip modem part of codec */
 #define AC97_SCAP_INDEP_SDIN	(1<<6)	/* independent SDIN */
 #define AC97_SCAP_INV_EAPD	(1<<7)	/* inverted EAPD */
+#define AC97_SCAP_DETECT_BY_VENDOR (1<<8) /* use vendor registers for read tests */
 
 /* ac97->flags */
 #define AC97_HAS_PC_BEEP	(1<<0)	/* force PC Speaker usage */

sound/pci/ac97/ac97_codec.c

@@ -1766,9 +1766,10 @@ void snd_ac97_get_name(ac97_t *ac97, unsigned int id, char *name, int modem)
 static int ac97_reset_wait(ac97_t *ac97, int timeout, int with_modem)
 {
 	unsigned long end_time;
+	unsigned short val;
+
 	end_time = jiffies + timeout;
 	do {
-		unsigned short ext_mid;
 		
 		/* use preliminary reads to settle the communication */
 		snd_ac97_read(ac97, AC97_RESET);
@@ -1776,17 +1777,24 @@ static int ac97_reset_wait(ac97_t *ac97, int timeout, int with_modem)
 		snd_ac97_read(ac97, AC97_VENDOR_ID2);
 		/* modem? */
 		if (with_modem) {
-			ext_mid = snd_ac97_read(ac97, AC97_EXTENDED_MID);
-			if (ext_mid != 0xffff && (ext_mid & 1) != 0)
+			val = snd_ac97_read(ac97, AC97_EXTENDED_MID);
+			if (val != 0xffff && (val & 1) != 0)
+				return 0;
+		}
+		if (ac97->scaps & AC97_SCAP_DETECT_BY_VENDOR) {
+			/* probably only Xbox issue - all registers are read as zero */
+			val = snd_ac97_read(ac97, AC97_VENDOR_ID1);
+			if (val != 0 && val != 0xffff)
+				return 0;
+		} else {
+			/* because the PCM or MASTER volume registers can be modified,
+			 * the REC_GAIN register is used for tests
+			 */
+			/* test if we can write to the record gain volume register */
+			snd_ac97_write_cache(ac97, AC97_REC_GAIN, 0x8a05);
+			if ((snd_ac97_read(ac97, AC97_REC_GAIN) & 0x7fff) == 0x0a05)
 				return 0;
 		}
-		/* because the PCM or MASTER volume registers can be modified,
-		 * the REC_GAIN register is used for tests
-		 */
-		/* test if we can write to the record gain volume register */
-		snd_ac97_write_cache(ac97, AC97_REC_GAIN, 0x8a05);
-		if ((snd_ac97_read(ac97, AC97_REC_GAIN) & 0x7fff) == 0x0a05)
-			return 0;
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		schedule_timeout(1);
 	} while (time_after_eq(end_time, jiffies));

sound/pci/intel8x0.c

@@ -68,6 +68,7 @@ static int enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;	/* Enable this card *
 static int ac97_clock[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 0};
 static int ac97_quirk[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = AC97_TUNE_DEFAULT};
 static int buggy_irq[SNDRV_CARDS];
+static int xbox[SNDRV_CARDS];
 static int boot_devs;
 
 module_param_array(index, int, boot_devs, 0444);
@@ -82,6 +83,8 @@ module_param_array(ac97_quirk, int, boot_devs, 0444);
 MODULE_PARM_DESC(ac97_quirk, "AC'97 workaround for strange hardware.");
 module_param_array(buggy_irq, bool, boot_devs, 0444);
 MODULE_PARM_DESC(buggy_irq, "Enable workaround for buggy interrupts on some motherboards.");
+module_param_array(xbox, bool, boot_devs, 0444);
+MODULE_PARM_DESC(xbox, "Set to 1 for Xbox, if you have problems with the AC'97 codec detection.");
 
 /*
  *  Direct registers
@@ -405,6 +408,7 @@ struct _snd_intel8x0 {
 	    in_sdin_init: 1;
 	int fix_nocache: 1; /* workaround for 440MX */
 	int buggy_irq: 1; /* workaround for buggy mobos */
+	int xbox: 1;	  /* workaround for Xbox AC'97 detection */
 
 	ac97_bus_t *ac97_bus;
 	ac97_t *ac97[3];
@@ -1907,6 +1911,8 @@ static int __devinit snd_intel8x0_mixer(intel8x0_t *chip, int ac97_clock, int ac
 	ac97.private_data = chip;
 	ac97.private_free = snd_intel8x0_mixer_free_ac97;
 	ac97.scaps = AC97_SCAP_SKIP_MODEM;
+	if (chip->xbox)
+		ac97.scaps |= AC97_SCAP_DETECT_BY_VENDOR;
 	if (chip->device_type != DEVICE_ALI) {
 		glob_sta = igetdword(chip, ICHREG(GLOB_STA));
 		ops = &standard_bus_ops;
@@ -2691,6 +2697,8 @@ static int __devinit snd_intel8x0_probe(struct pci_dev *pci,
 	}
 	if (buggy_irq[dev])
 		chip->buggy_irq = 1;
+	if (xbox[dev])
+		chip->xbox = 1;
 
 	if ((err = snd_intel8x0_mixer(chip, ac97_clock[dev], ac97_quirk[dev])) < 0) {
 		snd_card_free(card);