I am supporting a Peripheral Controller Driver (PCD)
for a USB device (hw and fw from a vendor) that
refuses to deliver data to its gadget driver client
when the data ends on a MaxPacketSize boundary (512 in
this case).
The requests submitted to the PCD have an 8K buffer
and the incoming data length happens to be 4K in this
case.
I believe a ZLP from the host would force this driver
to deliver the data in a partially filled buffer to
the gadget driver, but I haven't verified this yet. It
appears that USB host drivers don't do this
automatically, and the apps I'm using don't either.
A workaround is for my gadget driver to submit
requests to the PCD that contain buffers which are
MAXP in size. This enables the PCD to either fill a
buffer or get a short packet interrupt. Not very
appealing due to the extra interrupt handling.
Any advice or shared experiences on solving this type
of problem would be appreciated.
Thanks,
Skip Rafferty
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