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Date: Wed, 4 Mar 2009 14:50:31 -0800
From: Sarah Sharp <sarah.a.sharp@linux.intel.com>
To: Yinghai Lu <yinghai@kernel.org>
Cc: Greg KH <gregkh@suse.de>, "Eric W. Biederman" <ebiederm@xmission.com>,
       Ingo Molnar <mingo@elte.hu>, linux-usb@vger.kernel.org,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: EHCI debug documentation
Message-ID: <20090304225031.GA13509@gamba.jf.intel.com>
References: <20090303235354.GA7145@gamba.jf.intel.com> <86802c440903031731x36c1180dk72a3631bb4397319@mail.gmail.com>
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On Tue, Mar 03, 2009 at 05:31:44PM -0800, Yinghai Lu wrote:
> On Tue, Mar 3, 2009 at 3:53 PM, Sarah Sharp <sarah.a.sharp@intel.com> wrote:
> > Greetings,
> >
> > You wrote the EHCI debug port patch for early printk back in July 2008
> > (commit 5c05917e7fe313a187ad6ebb94c1c6cf42862a0b). ?Can you add some
> > documentation to the Documentation directory about how a Linux user
> > would set up a system (cables, files to open to get the printks, etc.)?
> 
> please check

This documentation looks fine, aside from the two comments below.  Can
you turn it into a patch, as Ingo suggested?  Thanks!

Sarah Sharp

> ==========================================================================================
> USB Debug port using Howto
> 
> 1. HW:
> 
> a. target system need to have debug port

(I assume the following output is from you running lspci -vvv as root,
so you should mention that in your documentation).

> 00:1d.7 USB Controller: Intel Corporation 82801H (ICH8 Family) USB2
> EHCI Controller #1 (rev 03) (prog-if 20 [EHCI])
>         Subsystem: Lenovo ThinkPad T61
>         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 D routed to IRQ 19
>         Region 0: Memory at fe227000 (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

What is the following output from?  Is it useful to the user setting up
the system? How are people supposed to decrypt this?

> 00: 86 80 36 28 06 01 90 02 03 20 03 0c 00 00 00 00
> 10: 00 70 22 fe 00 00 00 00 00 00 00 00 00 00 00 00
> 20: 00 00 00 00 00 00 00 00 00 00 00 00 aa 17 ab 20
> 30: 00 00 00 00 50 00 00 00 00 00 00 00 0b 04 00 00
> 40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 50: 01 58 c2 c9 00 80 00 00 0a 00 a0 20 00 00 00 00
> 60: 20 20 9f 01 00 00 00 00 01 00 00 01 00 00 08 80
> 70: c0 00 17 3f 00 00 00 00 00 00 00 00 00 00 00 00
> 80: 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00
> 90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> d0: 00 00 00 00 00 aa ff 00 00 00 00 00 00 00 00 00
> e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> f0: 00 00 00 00 88 85 40 00 86 0f 05 00 06 17 02 20
> 
> b. netchip USB debug cable
> 
> c. console system: have USB port
> 
> 2. SW setting
> a. console system: need to have kernel config
>    CONFIG_USB_SERIAL_DEBUG
>    you should get /dev/ttyUSBx
> 
>    # cat /dev/ttyUSBx could get output
> 
> b. target system: need to have kernel config
>    CONFIG_EARLY_PRINTK_DBGP
> 
>    boot command line: earlyprintk=dbgp
> 
> c. for Nvidia Southbridge based system: kernel will try to probe and
> find out which port has debug device connected.
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