Re: [PATCH] [media] rc: do not sleep when the driver blocks on IR completion

[Sean Young <sean@mess.org>]

On Sat, Aug 25, 2012 at 11:25:26AM +0200, David Härdeman wrote:
> On Sat, Aug 25, 2012 at 12:26:25AM +0100, Sean Young wrote:
> >On Sat, Aug 25, 2012 at 12:05:18AM +0200, David Härdeman wrote:
> >> On Thu, Aug 23, 2012 at 10:18:35PM +0100, Sean Young wrote:
> >> >Some drivers wait for the IR device to complete sending before
> >> >returning, so sleeping should not be done.
> >> 
> >> I'm not quite sure what the purpose is. Even if a driver waits for TX to
> >> finish, the lirc imposed sleep isn't harmful in any way.
> >
> >Due to rounding errors, clock skew and different start times, the sleep 
> >might be waiting for a different amount of time than the hardware took 
> >to send it. The sleep is a bit of a kludge, let alone if the driver
> >can wait for the hardware to tell you when it's done.
> 
> I don't see the sleep as much of a problem right now. Whether the
> hardware says its done or if we simulate the same thing in the lirc
> layer, the entire concept is a bit of a kludge :)

It's not making it any better.

> >Also, your change calculates the amount of us to sleep after transmission, 
> >so if the transmission buffer was modified by the driver, the calculated 
> >sleep might not make sense. Both winbond-cir and iguanair do this.
> 
> Oh, right, I'd overlooked this. I have written patches for winbond-cir
> (which makes it asynchronous and leaves the txbuffer alone) and iguanair
> (to leave the txbuffer alone). I'll post them sometime today when I've
> done some more tests.

If this is the solution we're going for, then I've got a patch for iguanair
which leaves the txbuffer alone and is ready and tested. I'll send it out
in the next half hour.


Sean