On Tue, 16 Apr 2013, victor yeo wrote:
> From the usbmon trace and driver log, i can only see that TEST UNIT
> READY command is sent out but UDC driver does not receive it. May i
> ask, under what circumstances, is gadget driver calling
> start_transfer() to schedule reading from bulk-out endpoint ?
file_storage.c calls start_transfer() whenever it expects the host to
send a bulk-out packet. These times include:
When the gadget is waiting for the host to send a CBW packet
containing a SCSI command;
When the gadget is waiting for the host to send the data part
of a WRITE command.
The driver also calls start_transfer() whenever it wants to send a
bulk-in packet to the host:
When the gadget wants to send the data part of a reply to a
command such as READ or READ CAPACITY;
When the gadget wants to send a CSW packet containing the
status of a completed SCSI command.
Alan Stern
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