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Re: RFC: gpio attachment for ppbus
On Tue, Apr 29, 2008 at 09:52:01AM -0400, der Mouse wrote:
> If that means it takes five syscalls to change five pins, I think I'd
> stick with hacking the lpt driver. But if there's some way to batch
> changes, to send many of them across the kernel/user boundary at once,
> it'd be somewhat awkward but probably OK.
Thats what I was thinking about. The pins would still be changed
sequentially, but without the overhead of syscalls.
> > There is also no distinction between data pins, status pins and
> > control pins, they are all just gpio pins.
> I wouldn't expect there'd be any difference at the API level, but there
> is a difference at the hardware level - as far as I can tell, you can
> change multiple data pins, or multiple control pins, simultaneously but
> you can't change data pins and control pins simultaneously, hence the
The whole gpio thing could be extended to support something like "pin
groups" that could be changed in one access, such a group would
correspond to a single device register. But this would also make the
gpio driver much more complicated.
%SYSTEM-F-ANARCHISM, The operating system has been overthrown
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