Re: Linux 3.8-rc1 - another regression on USB :-(

[Woody Suwalski]

Greg Kroah-Hartman wrote:
> On Sun, Dec 23, 2012 at 02:35:49PM -0800, Linus Torvalds wrote:
> > Woody,
> >   Any chance you can bisect this? It's not going to be hugely pleasant
> > (with 11k+ commits in between 3.7 and 3.8-rc1 you'll have to compile
> > and test at least 14 kernels), but it would help enormously. Of
> > course, maybe some USB person can guess what would cause the device to
> > go offline..
> >
> > Added Greg and the linux-usb mailing list to the participants list:
> > the images are in the original email on lkml, but there isn't anything
> > particularly interesting there, it really just seems to be an
> > unexpected and spurious USB disconnect, resulting in "USB disconnect,
> > device number 2" followed by "Rejecting I/O to offline device".
> I don't see any images on lkml, sorry.
>
> The kernel log for when the disconnect happened would be great to get.
>
> The kernel can't cause a device to disconnect, that's an electrical
> thing usually, is this perchance a flaky device/connection?  Or has it
> always worked on older kernels?
>
> What host controller is being used here (xhci, ehci, etc.?)
>
> thanks,
>
> greg k-h
Greg, Linus,
It sounds insane, but after banging on the issue I have found out that 
USB problem is caused (also in vanilla kernel) with a config change:
USB-all built as modules - bad USB
USB core built in, UHCI/EHCI modules -  semi functional - but 1Mb/s transfer
USB core and UHCI EHCI built-in - bingo - no issues.

Could anybody duplicate that, or is it somehow my setup???

Thanks, Woody

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