Alright, here we go, take 2.
Description:
Setting the event character and latency timer can greatly improve performance for some applications which use the ftdi_sio module (a serial->USB converter). The following patch adds sysfs attributes, exposing these configuration registers.
This is a patch against 2.6.10-rc2, but it also applies cleanly to 2.6.9. It works very nicely on 2.6.9, however I can't get my machine to boot 2.6.10-rc2, so I have been unable to test it on 2.6.10-rc2.
Food for thought: perhaps if low_latency is set we should reprogram the latency timer automatically. The default is 16ms, which can fairly attrocious for performance. Setting it *very* low, i.e., <=2 ms, degrades throughput on my machine-- I suspect the ftdi gets impatient too quickly, and commits to sending a frame before enough characters have come in to make it worthwhile (and sending a frame takes a while.) But we could probably drop the latency to around 4-6ms, with virtually no downside.
Signed-off-by: Edwin Olson ([EMAIL PROTECTED])
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