On Mon, 19 Jan 2009, Julie Zhu wrote: > > In theory this should work okay. It's not clear why your host > > controller dies. It could be a bug in the hardware design. > > > > I suspect a hardware bug too. Can you give me some pointer of what I > should expect if the host controller does not support FS/LS, and a FS/LS > device connects to the host controller? I don't know of any particular documentation. What should happen is that ehci-hcd will set the OWNER bit in the port-status register and the device will appear to have disconnected. The OWNER bit should get cleared by the hardware when the device is physically unplugged, even though there's no software notification. Maybe the implementation of the OWNER bit is broken. > I know, but it seems make some sense on embedded systems. For example, a > HS video camera, or a USB stick are the only expected devices that will > connect to your system. However, sometimes, a user may mistakenly plug > in a non-HS device. We would like to tell the user about his/her > mistake, however, keep the host controller alive. I think the kernel messages you're already getting will indicate the mistake. If you want, you can modify ehci-hub.c to print a warning message when a non-high-speed device is discovered. The real problem is to keep the controller alive. Since we don't know why it is dying, this is difficult... :-) > I do have USB_DEBUG configured in the kernel, however, I do not get any > print on the embedded system. Strange though, if I put some printk's, > and omit and "\n", some debug message will show up, however, not all of > them. You should post the dmesg log showing what happens. > I did have USB_MON configured in, however, at kernel start up, it > says: > > usbmon: debugfs is not available You need to enable CONFIG_DEBUG_FS. See the instructions in Documentation/usb/usbmon.txt. Alan Stern -- 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
