From: Jagadeesh Bhaskar Pakaravoor <j-pakaravoor@xxxxxx>
Following patch taken over the omapzoom.org tree fixes OMAP 3430
errata 1.11 for I2C: if the I2C module is configured as slave,
in autoidle mode (I2C_SYSC.AUTOIDLE=1) and the ARDY (I2C.I2C_STAT[2])
condition and the START condition are detected in the module at the
same time, internal clock gating will be wrongly applied. This will
cause the I2C to NACK (I2C.I2C_STAT[1])the transfer for which the
START (I2C.I2C_STAT[6]) condition was received. Next transfers will
be ACKed as expected.
Fix disables AUTO_IDLE from the start of a transaction, in slave
mode, till the end of it.
Signed-off-by: Jagadeesh Bhaskar Pakaravoor <j-pakaravoor@xxxxxx>
Index: 34+_master/drivers/i2c/busses/i2c-omap.c
===================================================================
--- 34+_master.orig/drivers/i2c/busses/i2c-omap.c 2008-09-29 18:18:35.000000000 +0530
+++ 34+_master/drivers/i2c/busses/i2c-omap.c 2008-10-01 13:12:29.299298673 +0530
@@ -544,6 +544,16 @@ omap_i2c_slave_xfer_msg(struct i2c_adapt
if (!(msg->flags & I2C_M_RD))
dev->slave_tx = 1;
+ /* As per OMAP3430 silicon errata 1.11, I2C in slave mode
+ * with AUTO_IDLE enabled can lead to race conditions. So disabling
+ * AUTO_IDLE for transactions in slave mode.
+ */
+ if (cpu_is_omap3430()) {
+ w = omap_i2c_read_reg(dev, OMAP_I2C_SYSC_REG);
+ w &= ~1;
+ omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, w);
+ }
+
dev->cmd_err = 0;
w = omap_i2c_read_reg(dev, OMAP_I2C_CON_REG);
w &= ~OMAP_I2C_CON_MST;
@@ -597,6 +607,7 @@ omap_i2c_xfer(struct i2c_adapter *adap,
struct omap_i2c_dev *dev = i2c_get_adapdata(adap);
int i;
int r;
+ u16 val;
omap_i2c_enable_clocks(dev);
@@ -632,6 +643,22 @@ omap_i2c_xfer(struct i2c_adapter *adap,
#endif
out:
disable_irq(dev->irq);
+
+ /* Switching to master mode */
+ val = omap_i2c_read_reg(dev, OMAP_I2C_CON_REG);
+ val |= OMAP_I2C_CON_MST;
+ omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, val);
+
+ /* As per OMAP3430 silicon errata 1.11, I2C in slave mode
+ * with AUTO_IDLE enabled can lead to race conditions. The AUTO_IDLE
+ * disabled at the beginning of a slave transaction is enabled back.
+ */
+ if (cpu_is_omap3430()) {
+ val = omap_i2c_read_reg(dev, OMAP_I2C_SYSC_REG);
+ val |= 1;
+ omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, val);
+ }
+
omap_i2c_disable_clocks(dev);
/* Default master mode */
dev->mode = OMAP_I2C_MASTER_MODE;
--
With Regards,
Jagadeesh Bhaskar P
----------------------------
Some men see things as they are and say why - I dream things that never were and say why not.
- George Bernard Shaw
-------------------
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