Delayed response to MBIM OPEN message

Ben Chan benchan at
Wed Feb 19 08:54:16 PST 2014

Hi Aleksander,

libmbim currently retries the OPEN message
(mbim-device.c:open_message) every 1s, if the modem does not respond.

However, MS recommends delaying MBIM OPEN
as follows:

"MBIM devices may require time to complete initialization when they
receive MBIM OPEN message from the host. The device should wait for
its initialization to complete before responding to the MBIM OPEN
message. The device should not respond to the message with error
status like MBIM_STATUS_BUSY and expect the host to poll the device
with MBIM OPEN messages. Responding to MBIM OPEN with a status other
than MBIM_STATUS_SUCCESS terminates the initialization process on the

>From my observation, it looks like modem vendors follow this
recommendation and delay the response to the OPEN message while the
modem is still initializing. The initialization process gets
unnecessarily terminated if libmbim retries the OPEN message too soon.
Other than letting libmbim to wait (much) longer before retrying the
OPEN message, I'm not sure if there is any better solution.

How do you think?


More information about the libmbim-devel mailing list