Hi, On Wed, Mar 16, 2016 at 02:33:19PM +0100, Pali Rohár wrote: > Hi! We found out that tpa6130a2 device is being initialized before > i2c_2 bus is initialized. So that is reason why tpa6130a2 fails... What do you mean by initialize? A call to tpa6130a2_probe()? In that case I wonder about client->adapter. Is it NULL? > Any idea why kernel first try to initialize one i2c device even before > bus itself is initialized? Just dump the stack during the tpa6130a2 initialization and you can see it in the kernel log: dump_stack(); --------------- I just had another look at the driver and I think there is a race condition for tpa6130a2_add_controls() and tpa6130a2_stereo_enable(). As far as I can see both functions check for "tpa6130a2_client != NULL". tpa6130a2_client is set before the probe function has finished, though. Simplified probe: ... tpa6130a2_client = client; set_default_regs(); acquire_power_gpio(); acquire_regulator(); tpa6130a2_power(1); // needs tpa6130a2_client check_device(); tpa6130a2_power(0); // needs tpa6130a2_client ... If tpa6130a2_add_controls() or tpa6130a2_stereo_enable() is called after tpa6130a2 probe has started, but before probe has completed, tpa6130a2_client is set, but not yet initialized. The race condition can be fixed easily by moving the tpa6130a2_client assignment directly after the regulator acquisition. -- Sebastian
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