Very nice, looks like we will be able to solve this issue. Thank you very much, Julie. > -----Original Message----- > From: Alan Stern [mailto:stern@xxxxxxxxxxxxxxxxxxx] > Sent: Monday, January 19, 2009 12:38 PM > To: Julie Zhu > Cc: linux-usb > Subject: RE: HCD_USB2 flag, ehci host controller, no FS/LS support > > 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 > This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately. -- 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
