AC97 register 0x54 is used by ICH to control GPIOs, which we don't want to access

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@6907 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/drivers/audio/ac97/ich/ac97.c

@@ -586,11 +586,6 @@ ac97_reg_is_valid(ac97_dev *dev, uint8 reg)
 		return false;
 
 	switch (dev->codec_id) {
-		case CODEC_ID_ALC201A:
-			if (reg != 0x54) /* reading register 0x54 causes a semaphore timeout on the next register accessed */
-				return true;
-			return false;
-
 		case CODEC_ID_AK4540:
 		case CODEC_ID_AK4542:
 			if (reg < 0x1e || reg == 0x20 || reg == 0x26 || reg > 0x7a)

src/add-ons/kernel/drivers/audio/ac97/ich/io.c

@@ -130,7 +130,10 @@ ich_codec_read(int regno)
 {
 	status_t rv;
 	ASSERT(regno >= 0);
+	ASSERT((regno & 1) == 0);
 	ASSERT(((config->type & TYPE_ICH4) != 0 && regno <= 511) || regno <= 255);
+	if (regno == 0x54) // intel uses 0x54 for GPIO access, we filter it!
+		return 0;
 	rv = ich_codec_wait();
 	if (rv != B_OK)
 		PRINT(("semaphore timeout reading register %#x\n",regno));
@@ -145,7 +148,10 @@ ich_codec_write(int regno, uint16 value)
 {
 	status_t rv;
 	ASSERT(regno >= 0);
+	ASSERT((regno & 1) == 0);
 	ASSERT(((config->type & TYPE_ICH4) != 0 && regno <= 511) || regno <= 255);
+	if (regno == 0x54) // intel uses 0x54 for GPIO access, we filter it!
+		return;
 	rv = ich_codec_wait();
 	if (rv != B_OK)
 		PRINT(("semaphore timeout writing register %#x\n",regno));