Re: EHCI debug documentation

[Ingo Molnar <mingo@elte.hu>]

* Randy Dunlap <randy.dunlap@oracle.com> wrote:

> 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
> > 
> > ==========================================================================================
> > USB Debug port using Howto
> > 
> > 1. HW:
> > 
> > a. target system need to have debug port
> > 
> > 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
> > 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
> 
> http://www.plxtech.com/products/NET2000/NET20DC/default.asp
> 
> 
> > 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.

Would be nice to turn this all into a patch that adds this info 
to Documentation/x86/early-printk.txt or so.

	Ingo