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--- In Eddie Dawydiuk <> wrote: > > Seeing as though the 10ms delay is not hardware specific, but rather > kernel specific Which brings up a question... While researching different ways to do various precision waits in linux, I found several mentions that the default 'jiffie' in the 2.6 kernel is 1ms, and approx one jiffie is the worst-case time that usleep() will take. So why did Technologic choose to use a 10ms jiffie in ts-linux? Is the ARM (ot specifically the TS board) hardware not capable of using the 1ms setting? The x86 board we're also using has a 2.6 kernel and usleep() never takes longer than 1ms (unless we ask it to). > I didn't add any comments. In my opinion comments > explaining how the Linux scheduler works don't belong in the ts7800ctl > utility source code. If I would have added a comment stating each sleep > may sleep for as long as 10ms, the comment would have been misleading. > As the comment would have made the assumption the kernel tick rate was > set to 100Hz. We can agree to disagree on that one. Since we're talking about code to talk to your particular implementation of the hardware, comments explaining the hardware's timing requirements (or lack thereof) would seem to be quite appropriate. Especially since usleep() is called with two apparently very different values (1 and 100), the code is very misleading as it is because it indicates that the short time may be necessary for part of the conversation, when that is not generally true. > > And generally is a very deliberate choice of words, because, > > at least on our board, ts7800ctl doesn't work 100% of the time. > > Sometimes it gets (and doesn't handle, but that's expected in a demo, I > > guess) errors selecting, reading or writing. And a couple times it just> > kinda hung until we killedi it. > > Interesting, this is the first report I've heard of such a failure. Can > you provide more information on how to reproduce this problem? Um, we used a brand new TS-7800 (ts7800ctl says it was 'born' on Jun 6, 2008), booted into the full linux that came on the board, downloaded ts7800ctl from the web site and ran it a number of times. When we started getting empty results (i.e. just a new command prompt) we tried using the VERBOSE option and saw it saying that it couldn't send a start signal or that the slave didn't ACK data. Simetimes after that it would just sit until we pressed enter again (it may have caused a serial glitch causing the console to miss the new prompt, I suppose) and sometimes we needed to press Ctrl+C to get a prompt back. Some of the experimentation with the watchdog also resulted in very strange results. For example, sometimes after the watchdog should hav e expired, we could still run a 'date' command, but nothing else. One time, I was able to alternate between 'date' and 'ls -l' but I couldn't run any other commands or even use 'ls' on any other directory. But even reading the MAC address, it would sometimes take two or three attempts before it succeeded and from then on (for that boot session) I think it worked every time (but I could be wrong). Lastly, has anyone else's TS-7800 been running (use the ts-7800ctl odometer) for under -16,000,000 hours? __._,_.___
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