James McMechan wrote:
> Well the API seems to still be moving as of 2.5.36
> What is the 2nd argument of usb_register_root_hub supposed to be?
That wasn't something that changed ... the answer is still the same:
its parent in the "device model" tree.
> Are there notes on how to build a HCD I have seen several sets on how to do
> a driver but since what I need to work on is a HCD they are less helpful. I
> think I understand how to relay the urbs and produce the fake hub but the
> various servcies registered and required seem to keep changing, some of
> which I can follow without too much trouble but others lose me.
There won't ever be that many HCDs, so specialized documentation is going
to be scarce since the main ones -- {E,O,U}HCI -- are already working.
The best I can offer now is to suggest studying ohci-hcd ... it's the
simplest of all those drivers (whew!) except maybe the SA-1111 support.
It dawned on me recently that one reason this seems so fuzzy is likely
that what you're doing is really writing a USB "host", and while the
hardware-specific HCD code (ehci-hcd, ohci-hcd, uhci-hcd) is distinct
from the rest of the host code, that's not the only "host" code!
Specifically, managing trees of USB devices (root and subsidiary hubs,
plus maybe TTs) through enumeration/disconnect is also purely a host
function, along with driver-to-interface binding.(*) It's naturally
a bit incestuous with the device model work, which also does that.
And doing all that through usbfs is (I've done it) rather painful.
What changed in 2.5.36 was innards of USB host support (use sharable
device model code, not USB-specific variants), but nothing related to
the HCD APIs (everything still talks to controllers the same way).
- Dave
(*) As is, oddly enough, the API for control transfers: just like bulk,
but with a setup packet on the side. On the device side, SETUP
handling needs to be more complex ... "gadget" code looks at the
SETUP to decide what kind of response to generate.
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