You wrote: > On Thursday, October 25, 2012 10:11:27 PM Rolf Eike Beer wrote: > > You wrote: > > > Hi Rolf, > > > > > > On Thu, Oct 25, 2012 at 02:59:49PM +0200, Rolf Eike Beer wrote: > > > > Hi all, > > > > > > > > as I found out the hard way tslib does the detection if a touchscreen > > > > has > > > > been "clicked" if the kernel driver says it does not support > > > > ABS_PRESSURE. But when the kernel says it can do ABS_PRESSURE tslib > > > > will > > > > not do it's emulation and just pass on whatever pressure value the > > > > kernel > > > > sends. > > > > > > > > So far, so good. Sadly there are some drivers that do: > > > > > > > > input_set_abs_params(dev, ABS_PRESSURE, 0, 0, 0, 0); > > > > > > What drivers are doing this? > > > > git grep 'ABS_PRESSURE, 0, 0, 0, 0' drivers/input/ > > > > > > Guess what happens: no clicks at all. The question I have is: does the > > > > above line make any sense to be in a kernel driver at all? Or is that > > > > some voodoo that must be there and it's all tslib fault? > > > > > > > > Now that I know where the problem is coming from the problem is easily > > > > fixable, I'm just wondering which patch to make. > > > > > > Well, the limits are strictly advisory for userspace, input core does > > > not perform any clamping or discarding the data that falls outside the > > > limits, so tslib probably should not do that either. > > > > My main concern is that if the driver says it will only ever give pressure > > values from 0 to 0, what useful stuff may that ever be? And since the > > driver says it supports presure touchscreen will wait for the driver to > > report it. Since it will never do it (or could at most return a 0), then > > there is nothing that could ever become a valid click event. > > Once again, the limits are simply advisory and can even be adjusted from > userspace (EVIOCSABS). > > So ucb1400_ts does report true pressure so all is good there, but tsc40 is > not. I think the claim for ABS_PRESSURE is left over from time when tslib > did not think that device without ABS_PRESSURE was a touchscreen. I'll > remove it from the driver. Thanks, so I know what part to patch. Please backport that to stable, too, so tslib will work with that driver even on stable kernels. Eike
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