Hello Timur,
Timur Tabi wrote:
Currently we define I2C_TIMEOUT like this:
#define I2C_TIMEOUT (CONFIG_SYS_HZ / 4)
I'm seeing some I2C instability on a new board I'm working on, especially with SPD. If I change the above to
#define I2C_TIMEOUT (CONFIG_SYS_HZ / 2)
The problems go away (or at least, so far appear to). Can someone tell me why we choose (CONFIG_SYS_HZ / 4) to begin with? The way we use I2C_TIMEOUT is confusing:
while (readb(&i2c_dev[i2c_bus_num]->sr) & I2C_SR_MBB) { if ((get_ticks() - timeval) > usec2ticks(I2C_TIMEOUT)) return -1; }
CONFIG_HZ is 1000, so I2C_TIMEOUT is equal to 250. However, the way it's used, 250 isn't the number of ticks per second, it's used as number of microseconds. If CONFIG_HZ is changed to 100, does that mean that we want to call usec2ticks(25)?
This seems like a Bug to me.
I think what we should be doing is this:
#define I2C_TIMEOUT 1000
Surely, one millisecond is not too long of a timeout?
I think this should be Ok. Can you provide a patch? Thanks for catching this.
bye Heiko