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List:       linux-usb
Subject:    EHCI debug - early printk
From:       Jason Wessel <jason.wessel () windriver ! com>
Date:       2009-04-30 11:51:23
Message-ID: 49F990BB.9020905 () windriver ! com
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I am having some issues trying to get one of those EHCI USB debug cables
to work with the hardware. 

I tried the USB debug cable with an Intel based laptop and desktop
system and neither worked.  Because the desktop system actually had a
rs232 port, I setup some early printk's to try to debug the early usb
initialization.  I found two different problems, and I was wondering if
any had an idea on what I might change to make it work, or how to
further diagnose the issue before believe that the HW broken in some way.

Problem 1)
The early printk's reported that the ehci reset was failing.

To work around this I just had the loop which tried only 10 times to
wait on the reset, try 100,000 times.  Perhaps this alone is the reason
it doesn't work, but it does seem as if the EHCI controller is out there
listening.

Problem 2)
The only USB device plugged in is the USB debug cable, and the driver
claims it cannot be found.  This is where I am stuck.  The early printk
out put is below.


Here is what lspci -vvv looked like for the device.
00:1d.7 USB Controller: Intel Corporation 82801G (ICH7 Family) USB2 EHCI
Controller (rev 01) (prog-if 20)
        Subsystem: Dell Device 01a8
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop-
ParErr- Stepping- SERR+ FastB2B- DisINTx-
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0
        Interrupt: pin A routed to IRQ 21
        Region 0: Memory at ffa80800 (32-bit, non-prefetchable) [size=1K]
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA
PME(D0+,D1-,D2-,D3hot+,D3cold+)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Debug port: BAR=1 offset=00a0
        Kernel driver in use: ehci_hcd
        Kernel modules: ehci-hcd


The device does work fine after the kernel loads the high level NetChip
debug driver.  The lsusb shows:

Bus 005 Device 002: ID 0525:127a Netchip Technology, Inc.
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          255 Vendor Specific Class
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0        64
  idVendor           0x0525 Netchip Technology, Inc.
  idProduct          0x127a
  bcdDevice            1.01
  iManufacturer           1 Ajays Technology
  iProduct                2 Ajays USB 2.0 Debug Cable
  iSerial                 3 Ajays001
  bNumConfigurations      1



And finally the early printk output:

dbgp_num: 0
Found EHCI debug port on 00:1d.7
bar: 10 offset: 0a0
bar_val: ffa80800 offset: 0a0
ehci_bar: ffffd800
debug_port: 1
n_ports:    8
portstatus1: 00001005
portstatus2: 00001000
portstatus3: 00001000
portstatus4: 00001000
portstatus5: 00001000
portstatus6: 00001000
portstatus7: 00001000
portstatus8: 00001000
ehci reset done
ehci started
No device found in debug port


Thanks,
Jason.
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