On Wed, Sep 12, 2012 at 04:51:40PM -0400, Alan Stern wrote: > On Wed, 12 Sep 2012, Michal Nowak wrote: > > > From https://bugzilla.kernel.org/show_bug.cgi?id=47421: > > > > I have problems with Samsung SCX-3205 scanner on Toshiba Satellite L855. > > When is scanner connected to the notebook (via USB) I can see it via > > `scanimage -L` on first attempt but on any other attempt I can't see it > > any more, unless I turn the scanner off and on. > > > > Currently using 3.5.3-1.fc17.x86_64 kernel (but it also happens with > > 3.6.0-0.rc4.git2.1.fc18). The latest working kernel is 2.6.39-1.fc16 on > > that hardware (2.6.40 which was in fact 3.0, I guess, does not work). > > > > That scanner with identical OS - Fedora 17 - worked well on Lenovo T510 > > (Sandy Bridge -- USB 2.0 only), the new Toshiba L855 (Ivy Bridge with > > USB 3.0 -- xHCI) fails here. > > > > I somehow think it's related to the xhci driver, hence Cc-ing Sarah. Is > > there a way how to disable xhci driver in favor of ehci (xhci and ehci > > are both compiled-in), so I can try with ehci? > > I can't help with the xHCI problem, but here's how you can disable the > xhci-hcd driver: > > echo 0000:00:14.0 >/sys/bus/pci/drivers/xhci_hcd/unbind I don't think unbinding the xHCI driver will switch the ports back to EHCI, unless xhci_shutdown is called when the driver is unbound, and Michal has the recent bug fix commit e95829f474f0db3a4d940cae1423783edd966027 "xhci: Switch PPT ports to EHCI on shutdown." Maybe a better way to test would be to blacklist the xHCI driver via a boot option. Then the EHCI driver won't switch over the Ivy Bridge USB ports to the xHCI host. However, I'm already aware that we have issues with scanners under Ivy Bridge xHCI, because I've gotten reports from other folks. I bought a scanner to try to reproduce it, but the scanner worked fine, so the issue might be related to a particular type of scanner. In all honesty, other bugs causing kernel crashes and failed suspends have taken higher priority than tracking down this bug. Still, it would be good to have more information. Would you be willing to run some tests for me? In particular, I need the dmesg with CONFIG_USB_DEBUG and CONFIG_USB_XHCI_HCD_DEBUGGING turned on, along with a usbmon trace of the scanner running twice under one of your EHCI-only systems, and a trace of two scans under xHCI. The documentation for how to capture a usbmon trace is in the kernel source directory in Documentation/usb/usbmon.txt. Sarah Sharp -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
