Hello Stefano,
just a question ...
Stefano Babic wrote:
There is sporadic failures when more as one I2C slave is on the bus and the processor tries to communicate with more as one slave. The problem was seen on a mx35pdk (two I2C slaves, PMIC controller and CAN/RTC chip).
The current driver uses the IIF bit in the status register to check if the bus is busy or not. According to the manual, this is not correct, because the IIB bit should be checked. Not only, to check if a transfer is finished must be checked the ICF bit, and this is not tested at all.
This patch comes from analyse with a corresponding driver provided by Freescale as part of the LTIB tool. Comparing the two drivers, it appears that the current u-boot driver checks the wrong bits, and depending on race condition, the transfer can be successful or not.
The patch gets rid also of own debug function (DPRINTF), replaced with the general debug().
Tested on Freescale mx35pdk.
Signed-off-by: Stefano Babic sbabic@denx.de CC: Heiko Schocher hs@denx.de
Changes:
Wolfgang Denk:
- change commit message explaining the problem
and the changes
- describe in commit message the drop of DPRINTF
drivers/i2c/mxc_i2c.c | 86 ++++++++++++++++++++++++++++++++++++++---------- 1 files changed, 68 insertions(+), 18 deletions(-)
diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c index fd6db18..c5ec486 100755 --- a/drivers/i2c/mxc_i2c.c +++ b/drivers/i2c/mxc_i2c.c
[...]
@@ -116,31 +113,61 @@ void i2c_init(int speed, int unused) i2c_reset(); }
+static int wait_idle(void) +{
- int timeout = I2C_MAX_TIMEOUT;
- while ((readw(I2C_BASE + I2SR) & I2SR_IBB) && --timeout) {
writew(0, I2C_BASE + I2SR);udelay(1);- }
- return timeout ? timeout : (!(readw(I2C_BASE + I2SR) & I2SR_IBB));
+}
static int wait_busy(void) {
- int timeout = 10000;
- int timeout = I2C_MAX_TIMEOUT;
- while (!(readw(I2C_BASE + I2SR) & I2SR_IIF) && --timeout)
while (!(readw(I2C_BASE + I2SR) & I2SR_IBB) && --timeout) udelay(1); writew(0, I2C_BASE + I2SR); /* clear interrupt */
return timeout;
}
+static int wait_complete(void) +{
- int timeout = I2C_MAX_TIMEOUT;
- while ((!(readw(I2C_BASE + I2SR) & I2SR_ICF)) && (--timeout)) {
writew(0, I2C_BASE + I2SR);udelay(1);- }
- udelay(200);
Why is this delay necessary? Why exactly 200? Is this documented somewhere in the doc?
bye, Heiko