linux-kernel - Re: Missing USB XHCI and EHCI reset for kexec

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Date:	Tue, 15 Apr 2014 21:08:12 +0200
From:	Stefani Seibold <stefani@...bold.net>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	linux-usb <linux-usb@...r.kernel.org>,
	linux-kernel@...r.kernel.org, Greg KH <greg@...ah.com>,
	sarah.a.sharp@...ux.intel.com, andreas.brief@...de-schwarz.com
Subject: Re: Missing USB XHCI and EHCI reset for kexec

Am Dienstag, den 15.04.2014, 15:05 -0400 schrieb Alan Stern:
> On Tue, 15 Apr 2014, Stefani Seibold wrote:
> 
> > > One other thing you can try is to increase the reset timeout in 
> > > drivers/usb/host/ehci-hub.c.  This is under the USB_PORT_FEAT_RESET 
> > > case in ehci_hub_control(), around line 1225:
> > > 
> > > 				/*
> > > 				 * caller must wait, then call GetPortStatus
> > > 				 * usb 2.0 spec says 50 ms resets on root
> > > 				 */
> > > 				ehci->reset_done [wIndex] = jiffies
> > > 						+ msecs_to_jiffies (50);
> > > 
> > > Increasing the 50 to 100 or more might help.
> > > 
> > > Alan Stern
> > > 
> > 
> > I tried this, when i increase the value to 1000, the reset and
> > enumeration process will be faster after a kexec: 28 Seconds vs. 162
> > Seconds.
> 
> Even 28 seconds is much longer than it should be.  And a 1000-ms long 
> reset signal is a lot longer than any device should need.
> 
> Anyway, since you saw the same problem after unbind and rebind, you 
> don't have to perform a kexec for testing.
> 

Right, but i would prefer a solution for this. Since it works perfectly
in kernel 3.4 i don't think it is a hardware issue.

- Stefani


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