Greg KH gregkh@suse.de writes:
On Fri, Dec 01, 2006 at 10:55:48AM -0800, Lu, Yinghai wrote:
-----Original Message----- From: Greg KH [mailto:gregkh@suse.de]
I can do that in about 15 minutes if you give me the device ids for the usb debug device that you wish to have.
Or you can also use the generic usb-serial driver today just fine with no modification. Have you had a problem with using that option?
We are talking about using USB debug device/EHCI debug port in LinuxBIOS in legacy free PC. Because one AM2+MCP55 MB doesn't have serial port.
I guess Eric is working on USB debug device/EHCI debug port for earlyprintk or printk.
Well, earlyprintk will not work, as you need PCI up and running.
And I have some code that barely works for this already, perhaps Eric and I should work together on this :)
I'd love to work with someone on this. I'm cc'ing Andi Kleen because he asked me where we had gotten on this the other day.
One big thing we need is a way to tell if you have the system booted if your device is plugged into the usb port that connects to the usb debug port. Figuring out which usb port you really have to plug into is still trying and error but at least being able to tell without having to try the code is good.
So here is my mostly somewhat working code. I don't understand what you have todo if you want to reset the device and then find the device so this code currently only works if you have ehci_hcd already loaded.
I am avoiding the pci bit simply by having someone pass me the hard coded numbers...
I think I can get it down to a single base address if I don't print debugging of which port you are plugged into, or try and debug the state out of reset.
usbtest.c is my little libusb client program. It's useful for exploring things.
usbdebug_direct.c is roughly a driver living in user space so I can debug the hard bits of the logic. Not a good production technique but great for prototyping. It has all of the basic primitives needed to actually use the ehci debug port.
The next big thing for me I guess is to modify a kernel and see what state the usb ports are in when I am booting and how much of the reset logic I need to understand to make this work. Greg I expect you understand that a little better than I do.
Eric