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Commit 14d178a1 authored by Kevin Hilman's avatar Kevin Hilman Committed by Russell King
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[ARM] 4140/1: AACI stability add ac97 timeout and retries 



Add timeouts to hardware read/write/probe functions in order
to avoid lockups on buggy/broken hardware.

Signed-off-by: default avatarKevin Hilman <khilman@mvista.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 41762b8c

sound/arm/aaci.c

+39 −11
Original line number Diff line number Diff line
@@ -65,10 +65,12 @@ static void aaci_ac97_select_codec(struct aaci *aaci, struct snd_ac97 *ac97) 
 *  SI1TxEn, SI2TxEn and SI12TxEn bits are set in the AACI_MAINCR

 *  register.

 */

static void aaci_ac97_write(struct snd_ac97 *ac97, unsigned short reg, unsigned short val)

static void aaci_ac97_write(struct snd_ac97 *ac97, unsigned short reg,

			    unsigned short val)

{

	struct aaci *aaci = ac97->private_data;

	u32 v;

	int timeout = 5000;



	if (ac97->num >= 4)

		return;
@@ -89,7 +91,11 @@ static void aaci_ac97_write(struct snd_ac97 *ac97, unsigned short reg, unsigned 
	 */

	do {

		v = readl(aaci->base + AACI_SLFR);

	} while (v & (SLFR_1TXB|SLFR_2TXB));

	} while ((v & (SLFR_1TXB|SLFR_2TXB)) && timeout--);



	if (!timeout)

		dev_err(&aaci->dev->dev,

			"timeout waiting for write to complete\n");



	mutex_unlock(&aaci->ac97_sem);

}
@@ -101,6 +107,8 @@ static unsigned short aaci_ac97_read(struct snd_ac97 *ac97, unsigned short reg) 
{

	struct aaci *aaci = ac97->private_data;

	u32 v;

	int timeout = 5000;

	int retries = 10;



	if (ac97->num >= 4)

		return ~0;
@@ -119,7 +127,13 @@ static unsigned short aaci_ac97_read(struct snd_ac97 *ac97, unsigned short reg) 
	 */

	do {

		v = readl(aaci->base + AACI_SLFR);

	} while (v & SLFR_1TXB);

	} while ((v & SLFR_1TXB) && timeout--);



	if (!timeout) {

		dev_err(&aaci->dev->dev, "timeout on slot 1 TX busy\n");

		v = ~0;

		goto out;

	}



	/*

	 * Give the AC'97 codec more than enough time
@@ -130,21 +144,35 @@ static unsigned short aaci_ac97_read(struct snd_ac97 *ac97, unsigned short reg) 
	/*

	 * Wait for slot 2 to indicate data.

	 */

	timeout = 5000;

	do {

		cond_resched();

		v = readl(aaci->base + AACI_SLFR) & (SLFR_1RXV|SLFR_2RXV);

	} while (v != (SLFR_1RXV|SLFR_2RXV));

	} while ((v != (SLFR_1RXV|SLFR_2RXV)) && timeout--);



	if (!timeout) {

		dev_err(&aaci->dev->dev, "timeout on RX valid\n");

		v = ~0;

		goto out;

	}



	do {

		v = readl(aaci->base + AACI_SL1RX) >> 12;

		if (v == reg) {

			v = readl(aaci->base + AACI_SL2RX) >> 4;

			break;

		} else if (--retries) {

			dev_warn(&aaci->dev->dev,

				 "ac97 read back fail.  retry\n");

			continue;

		} else {

		dev_err(&aaci->dev->dev,

			dev_warn(&aaci->dev->dev,

				"wrong ac97 register read back (%x != %x)\n",

				v, reg);

			v = ~0;

		}



	} while (retries);

 out:

	mutex_unlock(&aaci->ac97_sem);

	return v;

}