On OMAP36/37XX the standard on chip pullups are not sufficient to ensure proper i2c operation without external pullups or switching to high speed mode and enabling special on chip pullups.
This is an issue for Beagle xM, which does not have external pullups on the expansion board i2c lines.
The issue manifests itself as an AL (arbitration lost) error when probing for a non-existent device (i.e. on a Beagle xM with no expansion boards attached). This issue does not occur on expansion boards that include pullups or on Overo 37XX COM's since they include pull-ups.
This patch fixes the issue by checking for the AL bit in the i2c_probe function.
Signed-off-by: Steve Sakoman steve.sakoman@linaro.org ---
diff --git a/drivers/i2c/omap24xx_i2c.c b/drivers/i2c/omap24xx_i2c.c index a72d1a1..fab49fd 100644 --- a/drivers/i2c/omap24xx_i2c.c +++ b/drivers/i2c/omap24xx_i2c.c @@ -329,7 +329,7 @@ int i2c_probe (uchar chip)
while (1) { status = wait_for_pin(); - if (status == 0) { + if (status == 0 || status & I2C_STAT_AL) { res = 1; goto probe_exit; }