On Fri, 20 Aug 2010 22:37:16 +0800, Ming Lei wrote: > 2010/8/20 Dennis Nezic > <dennisn@xxxxxxxxxxxxxxxxxx>: > > On Fri, 20 Aug 2010 10:27:53 -0400 (EDT), Alan Stern wrote: > >> On Thu, 19 Aug 2010, Dennis Nezic wrote: > >> > >> > Gah. You're right! The drive works fine (at usb2 speeds / ehci) > >> > on my other linux laptop (the one that had MSWindows > >> > previously)!? > >> > > >> > So it works with: > >> > 00:1d.7 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW > >> > (ICH6 Family) USB2 EHCI Controller (rev 04) > >> > > >> > But not with: > >> > 00:13.2 USB Controller: ATI Technologies Inc IXP SB400 > >> > USB2 Host Controller > >> > > >> > Why? :S > >> > >> How would I know? I already told you my best guess: The hardware > >> is slightly miscalibrated, and as a result that particular > >> controller doesn't work well with that particular device. While > >> it might be caused by a hardware bug in the controller, it's hard > >> to know what that bug is or how to work around it. > >> > >> Do other high-speed devices work okay with the SB400 controller? > > > > Yes, i've used a bunch of usb2 devices before without any problems. High-speed too -- I.e. IDE harddrive enclosures at ~20+MB/sec. > > Any suggestions on how to go about debugging this? Some kind of > > usb-wire sniffer? > > Maybe the controller does not pass usb certification. > > If you do want to know the reason, you can test the eye diagram of the > usb host controller. Anybody with an oscilloscope and an SB400 usb controller (or 058f:6366 Alcor Micro Corp usb-storage device?) want to test the eye? :D -- 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
