Re: [PATCH] Re: [Bug #10713] ehci splatter in 2.6.26-rc2

From: Alan Stern
Date: Tue May 20 2008 - 11:36:31 EST


On Tue, 20 May 2008, Lennert Buytenhek wrote:

> Well. I just re-tested it a couple more times to be sure, and the
> "hcd->has_tt = 1;" line does make all the difference in the world when
> it comes to getting oopses on plugging in low speed USB devices on this
> board. So if you don't understand what's going on then I guess I don't
> either.
>
>
> > That has_tt flag isn't used anywhere in ehci-hcd (it is only
> > ever set, never read), and the only place it is used in usbcore is for
> > adjusting the root hub's device descriptor.
>
> Maybe this code in drivers/usb/core/hub.c has something to do with
> it?
>
> switch (hdev->descriptor.bDeviceProtocol) {
> case 0:
> break;
> case 1:
> dev_dbg(hub_dev, "Single TT\n");
> hub->tt.hub = hdev;
> break;
> case 2:
> ret = usb_set_interface(hdev, 0, 1);
> if (ret == 0) {
> dev_dbg(hub_dev, "TT per port\n");
> hub->tt.multi = 1;
> } else
> dev_err(hub_dev, "Using single TT (err %d)\n",
> ret);
> hub->tt.hub = hdev;
> break;
> default:
> dev_dbg(hub_dev, "Unrecognized hub protocol %d\n",
> hdev->descriptor.bDeviceProtocol);
> break;
> }

That must be it. This code base is getting too large to keep in a
single mind...

Looks like you should submit your patch.

Alan Stern


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