[PATCH] ARM: OMAP: Make AIC23 sound work again

[Dirk Behme <dirk.behme@googlemail.com>]

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Hack to add I2C zero length transfers and SMBus quick mode
necessary for AIC23 sound again.

Signed-off-by: Dirk Behme <dirk.behme_at_gmail.com>



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Index: linux-osk/drivers/i2c/busses/i2c-omap.c
===================================================================
--- linux-osk.orig/drivers/i2c/busses/i2c-omap.c
+++ linux-osk/drivers/i2c/busses/i2c-omap.c
@@ -285,20 +285,29 @@ static int omap_i2c_xfer_msg(struct i2c_
 			     struct i2c_msg *msg, int stop)
 {
 	struct omap_i2c_dev *dev = i2c_get_adapdata(adap);
+	u8 zero_byte = 0;
 	int r;
 	u16 w;
 
 	dev_dbg(dev->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
 		msg->addr, msg->len, msg->flags, stop);
 
-	if (msg->len == 0)
-		return -EINVAL;
-
 	omap_i2c_write_reg(dev, OMAP_I2C_SA_REG, msg->addr);
 
-	/* REVISIT: Could the STB bit of I2C_CON be used with probing? */
-	dev->buf = msg->buf;
-	dev->buf_len = msg->len;
+	/* Sigh, seems we can't do zero length transactions. Thus, we
+	 * can't probe for devices w/o actually sending/receiving at least
+	 * a single byte. So we'll set count to 1 for the zero length
+	 * transaction case and hope we don't cause grief for some
+	 * arbitrary device due to random byte write/read during
+	 * probes.
+	 */
+	if (msg->len == 0) {
+		dev->buf = &zero_byte;
+		dev->buf_len = 1;
+	} else {
+		dev->buf = msg->buf;
+		dev->buf_len = msg->len;
+	}
 
 	omap_i2c_write_reg(dev, OMAP_I2C_CNT_REG, dev->buf_len);
 
@@ -383,7 +392,7 @@ out:
 static u32
 omap_i2c_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }
 
 static inline void


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