Ian Abbott wrote:
On 25/10/2005 19:10, Paulo Marques wrote:
I'll do some more tests with a more recent kernel, to try to get more
debug information...
Good luck!
Its been a long time, but I just wanted to send the info I found to
finish up this thread and have this archived for future reference...
After applying a slab-owner patch to find out who was requesting
all that data, I found out that it was actually ftdi_write that was
being called thousands of times.
I inserted a dump_stack every 1024 calls to see the call chain leading
to that, and this is a typical path:
dumping ftdi_write (count 1 data[0] == 0x41)
[<c02c6403>] ftdi_write+0x93/0x2fb
[<c02bc7cb>] serial_write+0x75/0x80
[<c01e8a32>] tty_default_put_char+0x1e/0x22
[<c01e94aa>] echo_char+0x48/0x68
[<c01e9f6b>] n_tty_receive_buf+0x652/0x9dc
...
So it is actually echoing back the chars that it is receiving :(
The sequence I use is something like:
# stty -F /dev/tts/0 3000000 raw
# cat /dev/tts/0 | xxd -g 1 -c 16
then, on another console:
# printf "command to request a frame" > /dev/tts/0
The "raw" in the stty should disable echoing, no?
Anyway, doing a small C program to do the same, and setting the tty
flags on the opened fd using cfmakeraw, worked out pretty well.
I guess I'll need to read more on the tty layer to avoid future noise.
Thanks for all the help,
--
Paulo Marques - www.grupopie.com
Pointy-Haired Boss: I don't see anything that could stand in our way.
Dilbert: Sanity? Reality? The laws of physics?
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