i2c-omap: OMAP3430 Silicon Errata 1.153

When an XRDY/XDR is hit, wait for XUDF before writing data to DATA_REG.
Otherwise some data bytes can be lost while transferring them from the
memory to the I2C interface.

Do a Busy-wait for XUDF, before writing data to DATA_REG. While waiting
if there is NACK | AL, set the appropriate error flags, ack the pending
interrupts and return from the ISR.
Signed-off-by: NMoiz Sonasath <m-sonasath@ti.com>
Signed-off-by: NVikram pandita <vikram.pandita@ti.com>
[ben-linux@fluff.org: fixed mail format and added i2c-omap to subject]
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

drivers/i2c/busses/i2c-omap.c

@@ -672,9 +672,10 @@ omap_i2c_isr(int this_irq, void *dev_id)
 			break;
 		}
 
+		err = 0;
+complete:
 		omap_i2c_write_reg(dev, OMAP_I2C_STAT_REG, stat);
 
-		err = 0;
 		if (stat & OMAP_I2C_STAT_NACK) {
 			err |= OMAP_I2C_STAT_NACK;
 			omap_i2c_write_reg(dev, OMAP_I2C_CON_REG,
@@ -764,6 +765,27 @@ omap_i2c_isr(int this_irq, void *dev_id)
 							"data to send\n");
 					break;
 				}
+
+				/*
+				 * OMAP3430 Errata 1.153: When an XRDY/XDR
+				 * is hit, wait for XUDF before writing data
+				 * to DATA_REG. Otherwise some data bytes can
+				 * be lost while transferring them from the
+				 * memory to the I2C interface.
+				 */
+
+				if (cpu_is_omap34xx()) {
+						while (!(stat & OMAP_I2C_STAT_XUDF)) {
+							if (stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
+								omap_i2c_ack_stat(dev, stat & (OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR));
+								err |= OMAP_I2C_STAT_XUDF;
+								goto complete;
+							}
+							cpu_relax();
+							stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
+						}
+				}
+
 				omap_i2c_write_reg(dev, OMAP_I2C_DATA_REG, w);
 			}
 			omap_i2c_ack_stat(dev,