Messages in this thread | | | From | (Eric W. Biederman) | Subject | Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support. | Date | Tue, 05 Dec 2006 04:18:30 -0700 |
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David Brownell <david-b@pacbell.net> writes:
> On Sunday 03 December 2006 9:09 pm, Eric W. Biederman wrote: >> >> My driver should be sufficient to work with any EHCI in a realatively >> clean state, and needs no special BIOS support just the hardware. >> This appears to be different than the way the windows drivers are >> using these debug devices. > > I'm glad to see someone finally got progress on this ... :) > > Separately, I forwarded some stuff I did last year ... maybe it'll help. > You seem to have gotten further. Have you also observed that the > NetChip device seems to have polarity issues, such that only one > end behaves properly?
I haven't yet. But I don't think I have actually tried turning the cable around in a very meaningful way yet either. Possibly this is something that has been fixed. I know there are some odd issues that I have encountered. Like occasionally I would need to stop the software on one side, or I would need to unplug it when things got sufficiently confused.
> Note that this should **NOT** be specific to x86_64, since pretty > much any PCI based EHCI can do this. I wouldn't be able to use > this on my NForce2 box, for example ...
So I took a quick look what it would take to do this truly generically and even initializing this generally when console code typically is registered looks like a problem. Although only because we don't get around to setting up pci_config space access helpers in a timely manner. To some extent that still sucks because you are still being initialized before the general ehci-hcd code.
Regardless an arch specific i386 variant was easy to throw together. It still needs a bit of work but it basically worked.
> As for EHCI registers, if this really _needs_ to live outside > of drivers/usb/host, then I'd suggest <linux/usb/ehci.h> for > the relevant declarations ... the <linux/usb/*.h> headers are > provided exactly for sharing such declaration between otherwise > unrelated parts of the tree.
Yep that sounds like the right thing to do. I think I at least need to be called from something outside of drivers/usb and may need the code there.
Doing this in a truly generic fashion looks like a major pain. Because all of the infrastructure needs to be fixed.
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