Re: [9fans] USB developments

[Fco.J.Ballesteros <nemo@plan9.escet.urjc.es>]

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I'm not a usb expert, but have done some hacking on it and
have been tempted (a few times) to clean up a bit the
usbd/drivers/#U relationship. We are also running for usb 2.0
devices, and have some of them around, including a touch screen.
BTW, the specs in the usb web site are pretty complete.

It would be great if you could Cc me any mail regarding this issue,
I might help.

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From: Lucio De Re <lucio@proxima.alt.za>
To: 9fans mailing list <9fans@cse.psu.edu>
Subject: [9fans] USB developments
Date: Thu, 15 Jan 2004 08:16:38 +0200
Message-ID: <20040115081637.M4316@cackle.proxima.alt.za>

Will the USB developers on Plan 9 please stand up, specially the
one with all the comments about how classes should not be managed
in usb/usbd?

I now have a surprising number of USB 2.0 peripherals as wells as
enough USB specifications to make me want to test them.

Let me list them, in case anyone wants me to test their efforts:

	HP ScanJet 5200 scanner
	Canon BJC-2100 colour printer
	Handspring Visor USB cradle
	external IDE drive enclosure with ISD-300 USB controller
	Speed Com+ USB modem (VD56US?)
	an as yet unconnectable Flash RAM reader/writer (Apacer thing)

I've been messing around with the existing code, including Richard
Miller's mass storage driver, but I'm only a little more familiar
with the goings on after all the source perusing and hacking.

I _have_ made a change to /sys/src/usb/usbd/device.c that allows
a configure index of -1 to be used to specify the first available
configuration as the external IDE enclosure I use has only
configuration 2 :-(  No use looking for 1 as usbd.c does in
enumerate(), specially when that is only a first stab at the real
thing as indicated by the /* TO DO */ comment.

My immediate question is whether it makes sense and is even possible
to imitate the behaviour of ip/ipconfig in the case of USB and, in
the instance I have in mind, mount the IDE driver (or the SCSI
driver or the generic "sd" driver, whichever comes closest after
making the necessary adjustments) on the appropriate desired port,
as ipconfig does with etherx and the TCP/IP stack?

If somebody cares to hold my hand while I misuse the last few days
of freedom I have left while the SO is overseas, I'd like to make
some progress on this score.

I have read the USB source code for Plan 9, if not in its entirety,
certainly a few important modules; I still don't understand
(conspicuous amongst many other issues) how isochronous transfers
are created or sustained (I presume the host controller does all
the hard work, if not, I'm missing a huge chunk of knowledge), and
Richard Miller has set me right on a few other issues indicative
of great ignorance on my part.

I have to admit I _like_ USB 2.0, although I am familiar with all
the complaints levelled at it and I believe Plan 9 can and ought
to support it wholeheartedly.  If I can help getting this right,
I'd really like to do it.

++L