Hi,

I'm currently using the i2c_nrfx_twi driver to process i2c transfers with some peripherals.
I have several slave units on the same i2c bus and use multi-threading to deal with all of them.

I have to face the problem that at least two threads have to use the i2c bus at the same time.
Unfortunately the i2c_nrfx_twi_transfer() function doesn't handle this issue and only returns
-EIO  even if the real problem comes from the busy state of the i2c bus:

nrfx_err_t res = nrfx_twi_xfer(&get_dev_config(dev)->twi,
                           &cur_xfer,
                           (msgs[i].flags & I2C_MSG_STOP) ?
                           0 : NRFX_TWI_FLAG_TX_NO_STOP);


        if (res != NRFX_SUCCESS) {
            LOG_ERR("Error nrfx_twi_xfer with %d", res);
            return -EIO;
        }

Easy workarounds was to :

1- Add another if case :
if (res != NRFX_ERROR_BUSY)
and return a -EBUSY

OR

2- Protect the function with a mutex and leaving the kernel handle this using the priority of each threads

I don't know if there are better/cleaner solution than these two ones but i would really appreciate some help

Thanks
Aurelien