Todd Fischer wrote:
It was straight forward to expose the UDC's capabilities to the gadget driver once I understood the gadget framework. I started with the test zero driver and a single bidi bulk endpoint entry. I had to scratch my head a bit trying to figure out why the zero driver couldn't use both directions when the parser in epautoconf.c used to identify the endpoint capabilities understood the concept of a bidi endpoint. After changing the table to contain two unidirectional entries instead of one bidi entry, the gadget drivers were happy.
Thing is, USB itself doesn't have the notion of "bidirectional endpoint" except for EP0. So the gadget api doesn't, and the host side API doesn't. You may need additional API calls, but for now I'd make them specific to your dm270_udc driver.
I have some notes about other aspects of the gadget framework I do not understand (like the zero field in a request), but am holding off asking questions or proposing changes to the DocBook documentation until the OTG changes settle out.
And there I was thinking the changes can't really settle until there's another implementation or two behind them! :)
Comments on what's in the gadget-2.6 tree (up at 2.6.8-rc2) would be useful. I think the shape is right, so not many more API changes should be needed.
Overall, I found the division between the gadget driver and the UDC driver to be well engineered. I didn't add any UDC specific changes to the gadget driver (except for the mod_data.release related code). There is only a couple of places in the UDC code where I am still confused (like the ZLP mentioned above).
Well, ask away! You've shaken loose some good issues with the mass storage class code.
I need to be brave and try the UDC with the network gadget driver and see what other UDC problems turn up.
That relies on full duplex transfers, but I'd hope it fails politely on hardware that might be better suited to HDLC style (serial-ish) links.
- Dave
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