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

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Message-ID: <20140414172520.Horde.a0pUS344KcjNMpOsLcnEXQ6@webmail.your-server.de>
Date:	Mon, 14 Apr 2014 17:25:20 +0200
From:	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


Zitat von Alan Stern <stern@...land.harvard.edu>:


>> <6>[  167.936921] usb 2-2.1: new full-speed USB device number 3  
>> using ohci-pci
>> <6>[  168.067890] usb 2-2.1: New USB device found, idVendor=076b,
>> idProduct=a021
>> <6>[  168.074871] usb 2-2.1: New USB device strings: Mfr=1, Product=2,
>> SerialNumber=0
>> <6>[  168.082226] usb 2-2.1: Product: Smart Card Reader
>> <6>[  168.086963] usb 2-2.1: Manufacturer: USB
>> <6>[  168.172893] usb 2-2.2: new low-speed USB device number 4  
>> using ohci-pci
>> <6>[  168.300839] usb 2-2.2: New USB device found, idVendor=0aad,
>> idProduct=0024
>> <6>[  168.307823] usb 2-2.2: New USB device strings: Mfr=1, Product=2,
>> SerialNumber=0
>> <6>[  168.315180] usb 2-2.2: Product: FrontPanel USB Keyboard
>> <6>[  168.320436] usb 2-2.2: Manufacturer: Rohde&Schwarz
>> <6>[  168.337895] input: Rohde&Schwarz FrontPanel USB Keyboard as
>> /devices/pci0000:00/0000:00:17.0/usb2/2-2/2-2.2/2-2.2:1.0/input/input0
>> <6>[  168.360988] input: Rohde&Schwarz FrontPanel USB Keyboard as
>> /devices/pci0000:00/0000:00:17.0/usb2/2-2/2-2.2/2-2.2:1.1/input/input1
>
> Since some devices work and some don't, maybe part of the problem lies
> in the particular devices.
>

The problem lies on the "Bus 001 Device 002: ID 0424:2514 Standard  
Microsystems Corp. USB 2.0 Hub", which hangs for arround 162 seconds  
after a kexec.

The "Bus 002 Device 003: ID 076b:a021 OmniKey AG CCID Smart Card  
Reader" and "Bus 002 Device 004: ID 0aad:0024 Rohde & Schwarz GmbH &  
Co. KG" are attached to this Hub.

An other PowerPC device which is nearly eactly the same HW but without  
this USB HUB works perfectly.

>> This is the output of lsusb:
>>
>> Bus 001 Device 002: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
>> Bus 001 Device 004: ID 0928:0007 Oxford Semiconductor, Ltd
>> Bus 002 Device 002: ID 0451:2036 Texas Instruments, Inc. TUSB2036 Hub
>> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
>> Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
>> Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
>> Bus 002 Device 003: ID 076b:a021 OmniKey AG CCID Smart Card Reader
>> Bus 002 Device 004: ID 0aad:0024 Rohde & Schwarz GmbH & Co. KG
>>
>> My old kernel 3.4 does not show this problem. Since kernel 3.10 i need
>> to reset to ehci-pci device when kexec. But this workaround does not
>> work any longer on kernel 3.14.
>
> Have you tried bisecting between 3.4 and 3.10 to find which commit
> caused the behavior to change?
>

I cannot do a besecting run for this PowerPC emebbed device, since  
there are some other patches like a BSP and older squashfs which are  
not available. Nearly all of this generated kernels will not boot and  
work. For X86 this is a easy job, but not for a "out of tree" PowerPC  
device.

> What about if you just do:
>
> 	rmmod ehci-pci
> 	modprobe ehci-pci
>

The kernel is monolitic because the USB HW is needed in a early boot  
stage. The problem also occurs with ehci-fsl used in by an other  
PowerPC device, which is a part of the SoC and is not attached to the  
PCI bus.

One thing is that the "echo 1  
 >/sys/bus/pci/drivers/ehci-pci/0000\:00\:17.2/reset" workaround will  
no longer work for kernel 3.14.

- Stefani


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