Messages in this thread | | | Date | Fri, 22 Oct 1999 17:13:35 -0700 (PDT) | From | Jeremy Fitzhardinge <> | Subject | RE: Rio filesystem |
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On 22-Oct-99 Steven_Hazel@trilogy.com wrote: > So you're saying the best way to handle this is to just do direct hardware > access from within the filesystem code? My biggest practical problem with > this is that it would require a version of mount which knows how to pass it > the appropriate parallel port info.
That's easy: mount -o lpio=0xXXX /dummy /mnt/rio Your filesystem will see the mount options as a string, which you can parse in any way you like. BTW, can you not use the standard printer port driver?
> Yeah, I need to just pause for a few milliseconds between parallel port > control operations. I've been (ab)using udelay, which has the > disadvantages that my delay times vary unacceptably much from system to > system and that it locks the system for frequent milliseconds-in-length > intervals during file transfers, which isn't acceptable. Blocking sleep > definitely sounds like the right way to go -- any idea where I can find > info on linux's provisions for doing this?
There's a thread on linux-kernel about this right now. See "schedule_timeout() semantics/usage?". A quick summary:
Andrea Arcangeli <andrea@suse.de>: > So the right way to unconditionally wait for 5 sec _if_ you are not > registered in any waitqueue and so if you can't be wakenup from a kernel > event (that is not a signal) is: > > __set_current_state(TASK_UNINTERRUPTIBLE); > schedule_timeout(5*HZ);
This restricts you to HZ resolution (often 100Hz, 10ms), which may be too coarse for you.
J
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