Re: BUG: one patch causes imx51 Babbage board detect usb hub failed

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On Thu, 17 May 2012, Richard Zhao wrote:

> commit 3d9545cc375d117554a9b35dfddadf9189c62775
> Author: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Date:   Mon Apr 23 13:54:36 2012 -0400
> 
>     EHCI: maintain the ehci->command value properly
>     
>     The ehci-hcd driver is a little haphazard about keeping track of the
>     state of the USBCMD register.  The ehci->command field is supposed to
>     hold the register's value (apart from a few special bits) at all
>     times, but it isn't maintained properly.
>     
>     This patch (as1543) cleans up the situation.  It keeps ehci->command
>     up-to-date, and uses that value rather than reading the register from
>     the hardware whenever possible.
>     
>     Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
>     Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> 
> 
> The above commit causes failure of imx usb host hub detection.
> 
> usb 1-1: new high-speed USB device number 2 using mxc-ehci
> hub 1-1:1.0: USB hub found
> hub 1-1:1.0: 7 ports detected
> mxc-ehci mxc-ehci.1: fatal error
> mxc-ehci mxc-ehci.1: HC died; cleaning up
> mxc-ehci mxc-ehci.1: force halt; handshake f5780344 00004000 00004000 -> -110
> mxc-ehci mxc-ehci.1: HC died; cleaning up
> usb 1-1: USB disconnect, device number 2

This doesn't have much useful information.  Can you post the dmesg log
showing what happens during startup with CONFIG_USB_DEBUG enabled and
the patch below applied?

Alan Stern




Index: usb-3.4/drivers/usb/host/ehci-hcd.c
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci-hcd.c
+++ usb-3.4/drivers/usb/host/ehci-hcd.c
@@ -353,6 +353,7 @@ static int ehci_reset (struct ehci_hcd *
 		dbgp_external_startup();
 
 	ehci->command = ehci_readl(ehci, &ehci->regs->command);
+	dbg_cmd(ehci, "post-reset", ehci->command);
 	ehci->port_c_suspend = ehci->suspended_ports =
 			ehci->resuming_ports = 0;
 	return retval;

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