gnupic: Re: [gnupic] Follow-up question to the thread about Ben's port of Brad's Lab2 to gpasm
Subject:
Re: [gnupic] Follow-up question to the thread about Ben's port of
Brad's Lab2 to gpasm
From:
Wojtek Zabolotny ####@####.####
Date:
3 Jan 2006 09:03:44 +0000
Message-Id: <43BA3D83.2040201@elektron.elka.pw.edu.pl>
Nicholas Robinson napisał(a):
>
>lsusb has never shown anything; occasionally I get some dmesg messages but not
>every time. I've once had a dmesg report that a high speed device had been
>connected but usually it's something along the lines of:
>
>Jan 2 15:41:30 paulo kernel: usb 2-1: new low speed USB device using uhci_hcd
>and address 11
>Jan 2 15:41:30 paulo kernel: usb 2-1: device descriptor read/64, error -71
>Jan 2 15:41:30 paulo kernel: usb 2-1: device descriptor read/64, error -71
>Jan 2 15:41:30 paulo kernel: usb 2-1: new low speed USB device using uhci_hcd
>and address 12
>Jan 2 15:41:30 paulo kernel: usb 2-1: device descriptor read/64, error -71
>Jan 2 15:41:30 paulo kernel: usb 2-1: device descriptor read/64, error -71
>Jan 2 15:41:31 paulo kernel: usb 2-1: new low speed USB device using uhci_hcd
>and address 13
>Jan 2 15:41:31 paulo kernel: usb 2-1: device not accepting address 13, error
>-71
>Jan 2 15:41:31 paulo kernel: usb 2-1: new low speed USB device using uhci_hcd
>and address 14
>Jan 2 15:41:32 paulo kernel: usb 2-1: device not accepting address 14, error
>-71
>
>when they get to syslog.
>
>
>
From my experience with USB firmware I can see that to obtain the above
messages it is enough to provide the proper pull-up. I obtained similar
results when my firmware was absolutely dead ;-).
If you want to see what's going on on the USB bus, then recompile your
kernel with debugfs (switch it on in "kernel hacking" section), then
mount debugfs somewhere (I usually do: "#mkdir /tmp/debug; mount mount
-t *debugfs* none /tmp/debug"), then insert the "usbmon" module.
It allows you to monitor the low level USB traffic. More info can be
found in: "Documentation/usb/usbmon.txt" in your kernel sources and
here: http://people.redhat.com/zaitcev/linux/OLS05_zaitcev.pdf
I've found the usbmon to be an essential tool when debugging USB
firmware without debugging capabilities on my target board...
--
HTH & Regards,
Wojtek Zabolotny
>I've taken Brad's config fuse settings as my starting point and changing them
>can result in the led failing to light, so they must be having an effect!
>
>I think this error code refers to 'Protocol Error' which seems reasonable
>enough.
>
>Best Wishes
>
>Nick
>
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