On Fri, Aug 30, 2002 at 12:20:11AM -0300, Lucas Correia Villa Real wrote:
> I'm playing around with a driver, but I would like to let applications
> based on that device hold on with a select() until some data come to the
> All I found about implementing this was looking at drivers/char/ppdev.c,
> but I find myself a little confused: to do that, I just need to add a IRQ
> handler on parport_register_device() that write_control() and
> wake_up_interruptible()? Why is there an atomic_inc()? What about
irqresponse here means 'is pp->irqctl valid', and that's why the
control line write is guarded by it. If PPWCTLONIRQ hasn't been
called, no write is needed.
The irqc atomic variable is a count of how many interrupts have
occurred since the last call to PPCLRIRQ.
If you aren't doing either of those things, you don't need the
atomic_inc or the irqresponse/write_control bit.
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