[U-Boot-Users] [PATCH 01/10] [ARM] MXC: insert bus busy check in i2c_probe

Jens Gehrlein
2008-07-04T14:50:04Z

On fast CPUs the time between two chip queries can become too short
to issue clear start and stop conditions. The bus seems to be blocked.
This cannot be compensated by just waiting for completed byte transfer.
The patch introduces polling of the bus busy bit in the I2C
controller's status register before the next bus access is possible.

Signed-off-by: Jens Gehrlein <sew_s@tqs.de>
---

drivers/i2c/mxc_i2c.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
index a218329..6f9306f 100644
--- a/drivers/i2c/mxc_i2c.c
+++ b/drivers/i2c/mxc_i2c.c
@@ -115,6 +115,16 @@ static int rx_byte(void)
int i2c_probe(uchar chip)
{
int ret;
+ int timeout = 100000;
+
+ /* Check if bus is busy before probing next chip */
+ while ((__REG16(I2C_BASE + I2SR) & I2SR_IBB) && --timeout)
+ udelay(1);
+
+ if (timeout == 0) {
+ printf ("\nerror: bus blocked\n");
+ return -1;
+ }

__REG16(I2C_BASE + I2CR) = 0; /* Reset module */
__REG16(I2C_BASE + I2CR) = I2CR_IEN;