Hello Peter,
30.01.2012 5:45, Chen Peter-B29397:
Is it normal that a gadget driver after creating a few IN endpoints does
not start feeding any Tx data to some of them?
Yes, it is possible. It is gadget itself behave, it can call ->ep_enable to
create class endpoints after receiving SetInterface(1,1), then ->ep_enqueue
is triggered by application.
I'm asking because I thought it is strange but specifically g_serial as
of 2.6.34 (can't test this on any newer yet) by default and while no-one
opens any ports yet (just cable plugged in), does this:
1. creates IN1 bulk, IN2 intr. (I'm omitting OUTs here)
2. enqueues something to IN2, but _never_ enqueues anything to IN1 as
far as I can see.
As soon as a token for IN1 arrives from the host, device driver gets
stuck waiting indefinitely because it has nothing to send. What should
it do in such case?
" waiting indefinitely" what do you mean? If there is no data to send, the
controller will send NAK automatically.
Ups, sorry, meant "infinitely" of course.
But how would the (device) driver destinguish between gadget not willing
to send any more data (intentionally) and not being fast enough to
finish preparing the appropriate request just yet?
Also, what should host do if it did not receive neither NAK nor data?
There has to be some timeout probably? I've noticed that occasional 3
second delays still do not harm the transfer here (other than slowing it
down).
Thank you.
Nikolai
Thank you.
Nikolai
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