David Brownell wrote:
On Tuesday 08 February 2005 1:03 am, Andi Kleen wrote:
BTW EHCI works, you just shouldn't use any USB 2.0 devices.
That is, the root hub "switch to the companion controller"
works, but not any other traffic? Then there's no point...
But there are valid reasons in some cases to want to have EHCI
even on a 8111, e.g. if you want to use the debug port.
The debug devices are USB 2.0 devices though ... albeit odd
ones!
It's annoying
to have to fight against such dumb code in the kernel then.
Do you actually have a debug port driver for Linux? And some
hardware that it can talk to?
I started looking at that issue a while back:
I started looking into one last week.
- What model to use for it? OK, "console" for output is
at least a (unidirectional) start; how about remote GDB?
Remote kgdb is what makes sense to me, just another kind
of serial device.
- But usually one wants consoles that start working well
before PCI is initialized.
- The EHCI driver currently doesn't know how to share
access to the debug port. ("mode 2" or whatever.)
It will have to be taught.
- OK, I can roll my own debug device using a net2280
and the g_serial driver. Not everyone has those...
More hardware seems to come without serial ports lately, so
it starts to look like Linux could benefit from a solution
there. (Actually several, but the EHCI debug port option
"ought to be" relatively accessible.)
Agreed.
The only USB debug device that I have been able to find is
this one:
http://store.yahoo.com/plxtech/net20dg.html
I've ordered one and will be beginning on supporting it RSN.
--
~Randy
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