i2c: omap: improve i462 errata handling

Make it not depend on ISR's local variables
in order to make it easier to re-factor the
transmit data loop.
Also since we are waiting for XUDF(Transmitter underflow) just before
writing data lets not flag the underflow.
This is anyways going to go once we write
the data.

Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

drivers/i2c/busses/i2c-omap.c

@@ -725,27 +725,30 @@ omap_i2c_omap1_isr(int this_irq, void *dev_id)
  * data to DATA_REG. Otherwise some data bytes can be lost while transferring
  * them from the memory to the I2C interface.
  */
-static int errata_omap3_i462(struct omap_i2c_dev *dev, u16 *stat, int *err)
+static int errata_omap3_i462(struct omap_i2c_dev *dev)
 {
 	unsigned long timeout = 10000;
+	u16 stat;
 
-	while (--timeout && !(*stat & OMAP_I2C_STAT_XUDF)) {
-		if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
+	do {
+		stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
+		if (stat & OMAP_I2C_STAT_XUDF)
+			break;
+
+		if (stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
 			omap_i2c_ack_stat(dev, (OMAP_I2C_STAT_XRDY |
 							OMAP_I2C_STAT_XDR));
-			return -ETIMEDOUT;
+			return -EIO;
 		}
 
 		cpu_relax();
-		*stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
-	}
+	} while (--timeout);
 
 	if (!timeout) {
 		dev_err(dev->dev, "timeout waiting on XUDF bit\n");
 		return 0;
 	}
 
-	*err |= OMAP_I2C_STAT_XUDF;
 	return 0;
 }
 
@@ -903,9 +906,16 @@ omap_i2c_isr(int this_irq, void *dev_id)
 					}
 				}
 
-				if ((dev->errata & I2C_OMAP_ERRATA_I462) &&
-				    errata_omap3_i462(dev, &stat, &err))
-					goto complete;
+				if (dev->errata & I2C_OMAP_ERRATA_I462) {
+					int ret;
+
+					ret = errata_omap3_i462(dev);
+					stat = omap_i2c_read_reg(dev,
+							OMAP_I2C_STAT_REG);
+
+					if (ret < 0)
+						goto complete;
+				}
 
 				omap_i2c_write_reg(dev, OMAP_I2C_DATA_REG, w);
 			}
@@ -943,9 +953,16 @@ omap_i2c_isr(int this_irq, void *dev_id)
 					}
 				}
 
-				if ((dev->errata & I2C_OMAP_ERRATA_I462) &&
-				    errata_omap3_i462(dev, &stat, &err))
-					goto complete;
+				if (dev->errata & I2C_OMAP_ERRATA_I462) {
+					int ret;
+
+					ret = errata_omap3_i462(dev);
+					stat = omap_i2c_read_reg(dev,
+							OMAP_I2C_STAT_REG);
+
+					if (ret < 0)
+						goto complete;
+				}
 
 				omap_i2c_write_reg(dev, OMAP_I2C_DATA_REG, w);
 			}