> Is there some webpage I read it to find out the status of USB 2.0 support
> in Linux ? (In particular the "highspeed mode" or whatever 480mbit/sec is
> called).
>
> If not, could some enlighten me ?
No webpage so far ... just try it out! Meanwhile:
linux/Documentation/usb/ehci.txt ... in 2.4.19-pre6 and 2.5.8
http://www.linux-usb.org/FAQ.html#gs6 ... about USB 2.0
Short version of the story is
USB 2.0 == USB 1.1
+ "high speed" (480 mbit/sec) busses and hubs
+ certification (two new logos; "highspeed" is two colors)
The highspeed controller standard is called EHCI, and has Linux support.
The USB 2.0 support includes hub and other usbcore updates, as well
as the "ehci-hcd" driver for those highspeed controllers.
The 2.5.8 "ehci-hcd" version is the most functional, and should work with
EHCI implementions from NEC, Intel, Philips, VIA, and maybe more.
It supports all four types of high speed transfers (control, bulk, interrupt,
and isochronous). I'll update the 2.4 version to match it at some point.
Currently the 2.4 driver is older: only NEC, no isochronous transfers.
The "split transaction" support through high speed hubs is only partially
functional so far though. Control and bulk transfers work through them,
at least until certain kinds of errors happen. The hub driver doesn't yet
know how to recover from those kinds of transaction translator error.
Also, there is no support yet for split periodic transactions; it'll be easier
for interrupt transfers (except scheduling) since split iso involves a new
way to talk to EHCI implementations. (That means: don't hook up USB 1.1
webcams, keyboards, mice, etc. to highspeed hubs, they'll enumerate
but you won't be able to use them otherwise.)
Linux USB 2.0 support seems to work pretty well for the usb-storage
devices that now exist (modulo some slowdown from the usb-storage
driver not queuing requests). That's all that most folk have so far, but
highspeed scanners and printers ought to be in the works too.
On the "develop a highspeed USB device" side, Cypress EZ-USB FX2
plays nicely with Linux. I'm also looking forward to the new PCI based
controller upcoming from NetChip ... that'll be practical to use in many
embedded "Linux device" configurations! :)
- Dave
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