i2c-pca: Fix waitforcompletion() return value

ret is still -1, if during the polling read_byte() returns at once
with I2C_PCA_CON_SI set. So ret > 0 would lead *_waitforcompletion()
to return 0, in spite of the proper behavior.

The routine was rewritten, so that ret has always a proper value,
before returning.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: stable@kernel.org
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/i2c/busses/i2c-pca-isa.c

@@ -71,8 +71,8 @@ static int pca_isa_readbyte(void *pd, int reg)
 
 static int pca_isa_waitforcompletion(void *pd)
 {
-	long ret = ~0;
 	unsigned long timeout;
+	long ret;
 
 	if (irq > -1) {
 		ret = wait_event_timeout(pca_wait,
@@ -81,11 +81,15 @@ static int pca_isa_waitforcompletion(void *pd)
 	} else {
 		/* Do polling */
 		timeout = jiffies + pca_isa_ops.timeout;
-		while (((pca_isa_readbyte(pd, I2C_PCA_CON)
-				& I2C_PCA_CON_SI) == 0)
-				&& (ret = time_before(jiffies, timeout)))
+		do {
+			ret = time_before(jiffies, timeout);
+			if (pca_isa_readbyte(pd, I2C_PCA_CON)
+					& I2C_PCA_CON_SI)
+				break;
 			udelay(100);
+		} while (ret);
 	}
+
 	return ret > 0;
 }