Re: [PATCH] input: evdev: Add a read() callback

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On Mon, Feb 21, 2011 at 10:33 PM, Mark Brown
<broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> But surely the most obvious solution here is to standardise a rate
> control interface?

Yes, and no.  A standardized rate control interface would deal with
the rate control problem, but leave the synchronization problem

> The problem you're trying to solve is also an issue for really common
> and standard things like touchscreens and polled switches/keys (the
> latter of which you mentioned in your mail) which are used by standard
> applications.

The existing "polled switch" implementation sets up a throttled
polling loop in kernel code.  The "polled switch" that I was thinking
of when I wrote the essay for the commit was "a switch that is polled
each time read() gets called".  I should have been clearer--- and
probably picked a different name.  :)

> Have you looked at the IIO subsystem for things like this?  There has
> been talk of putting accelerometers in there and it certainly fits in
> with the sync requirements you're mentioning.

Now that I have found the code, I'm looking at it.  Can't say yet
whether it's the solution I'm seeking, or not.

> The problem with your proposal as it stands is that if they do use the
> new interface they interact badly with existing applications.  This
> isn't really a decision the driver should be taking, it needs to be
> userspace policy if it's going to be a decision at all.

Yea, I'm agreeing with you more than I was at the beginning of this thread.

Bill Gatliff
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