The zeroing of I2Ci.I2C_CNT register at the end of i2c_write causes random I2C failures in OMAP3 based devices. This is probably related to the following advisory in OMAP3 errata:
I2C Module Does Not Allow 0-Byte Data Requests Details: When configured as the master, the I2C module does not allow 0-byte data transfers. Note: Programming I2Ci.I2C_CNT[15:0]: DCOUNT = 0 will cause undefined behavior. Workaround(s): No workaround. Do not use 0-byte data requests.
Make the write conditional so that only non-OMAP3 devices will perform it.
Cc: Heiko Schocher hs@denx.de Signed-off-by: Nikita Kiryanov nikita@compulab.co.il --- drivers/i2c/omap24xx_i2c.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/i2c/omap24xx_i2c.c b/drivers/i2c/omap24xx_i2c.c index 3d38c03..2862a8f 100644 --- a/drivers/i2c/omap24xx_i2c.c +++ b/drivers/i2c/omap24xx_i2c.c @@ -473,7 +473,10 @@ static int omap24_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr, wr_exit: flush_fifo(adap); writew(0xFFFF, &i2c_base->stat); + /* This write is known to cause undefined behavior on OMAP3 */ +#ifndef CONFIG_OMAP34XX writew(0, &i2c_base->cnt); +#endif return i2c_error; }