On Tue, 12 Jun 2007, Tomohiro Kusumi wrote: > Hi Alan > > > This could be a problem with the BIOS. You might try going through the > > BIOS setup and turning off support for Legacy USB or anything else > > which might cause the BIOS to interfere with USB operations. > > Thanks for pointing out the possible BIOS problem regarding > the EHCI port status register problem a few weeks ago. > I went through the BIOS setup but all the Legacy USB stuffs > are turned off. Changing USB settings didn't affect the result. > > So right now I'm trying to see if I can make workaround by changing > ehci_hub_status_data() function. As I've explained before, the problem > is that the port status register is 0x1005 when it should be something > like 0x1803. As a result ehci_hub_status_data() returns 0 and > mod_timer(hcd->rh_timer, jiffies+HZ/4) is called forever. > > I tried to write 0x1803 to the register when it has 0x1005, > but it didn't work. It got back to 0x1005 when ehci_hub_status_data() > is called next time. > > Up until the 2.6.21 kernel (I'm using 2.6.9) it seems that the logic > hasn't been changed much, which continues to do ehci_hub_status_data() > until certain bits are turned on. Is it possible to get out of this > timer function loop, and let the driver detect the USB device? > Any suggestions would be helpful.
The easiest solution is to replace your EHCI hardware with a non-broken controller. But if you want a software workaround, here's what you can do. During ehci_irq() when you see that connect-change bit is on, you should set a bitflag. Turn off the bitflag in ehci_hub_control() when you get a ClearPortFeature request for USB_PORT_FEAT_C_CONNECTION. Then use the bitflag in ehci_hub_status_data() and in the GetPortStatus case of ehci_hub_control(); when the flag is set turn on the appropriate bit of the return value. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
