Wolfgang -
Aaah... the user should not be able to send the second command, if the first command is not finished. So you basicly have 2 choices: a) let the user write() function sleep (=blocking) until the first command is finished.
This _would_ be ideal except I would need a way to signal the write command to unblock. This is impossible because I would have to signal from the send callback which is in_interrupt.
OR b) insert the user commands into a queue and process them one-by-one. This approach is used in the auerswald driver (usb/misc/auerswald), which I wrote (but without kernel timers, of course).
This should work and is essentially the same as the circular buffer method I proposed a few emails ago.
> But, changing the frequency requires a > sleep, so I cannot call it from in_interrupt (the receive > callback or timer. If you use kernel timers, why do you want to call sleep()?
Well, because tuning the radio requires two commands to be sent. The commands must have a delay between them. So, I am unable to execute tune() from a timer or urb callback function. Note, I must wait for a report to be sent from the device before calling tune() again. Now, if I use the queue technique I could just put both commands on the queue where the dispatcher will handle the timing.
> And it would be a plus if the user can call > seek asynchronously as well since it can take up to 20 seconds to > check the whole FM band and I don't want to require knowledge of > threads. So, for seek() commands, you will have only two seek commands a) the command which is executed b) the command which waits until a) is finished.
Yes, this should work reasonably well with the queue technique. I could easily implement a). But how do I let b) block until a) is finished? There is no way to signal from in_interrupt. Thanks, Paul Paul
If there is a third seek() if b) is waiting, throw away b) and insert the new seek. regards Wolfgang -- We're back to the times when men were men and wrote their own device drivers. (Linus Torvalds)
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