On Fri, Oct 22, 2010 at 08:16:48AM +0100, Hennerich, Michael wrote: > Dmitry Torokhov wrote on 2010-10-22: > > Hi Michael, > > > > On Mon, Oct 18, 2010 at 03:33:24PM +0200, michael.hennerich@xxxxxxxxxx > > wrote: > >> From: Michael Hennerich <michael.hennerich@xxxxxxxxxx> > >> > >> Considering following scenario - the touch is present on the screen at > >> the beginning of the last conversion sequence, but by the time the last > >> sequence is finished, the finger is lift off. The AD7879 data available > >> interrupt signals (DAV) completion, however some X,Y values are not > >> valid because the screen inputs were floating during the acquisition. > >> > >> The AD7877 acts differently here, since it only asserts DAV if the > >> touch is still present when the conversion sequence finished. > >> > >> Based on the fact that this can only happen in the last sample of the > >> repeated conversion sequence. We simply skip the last. (Short glitches > >> are filtered by the AD7879 internal median and average filters) This > >> doesn't cause noticeable side effects, since the minimum conversion > >> interval is 9.44ms. We receive ~100 waypoint samples per second, so we > >> simply delay the result by 9.44ms. > >> > >> Actually this patch repeats the first waypoint twice and then skips > > the last. > > > > Input core won't actually pass the 2nd instance through. I think the > > whole thing should look like the patch below. > > I know input core suppresses identical events. > Your patch looks nicer, however it will delay the first response by one > Interrupt. Considering the minimum automatic conversion interval of 9.44ms > - Not sure how much this really matters. > > Acked-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx> > Thanks Michael. I think 10-15ms delay should not be noticeable for user input, however you have the hardware, any chance you could try and see? -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
