Hi Dmitry! On Fr, 2009-12-04 at 15:49 -0800, Dmitry Torokhov wrote: [...] > > Given this behaviour of the hw, I'd favour not reporting button presses > > on a device while the corresponding button on the other device is down. > > (Dave called this behaviour 'masking'.) Code implementing this was in > > the patch I sent to linux-input dated Nov. 11 (see the parts involving > > the btn_state variable). I have not put it back in the patch below > > because I'd like to await your opinion on this first. > > OK, Let me take a look at that patch again. I think it's pretty straightforward. Let me know what you think. > > There is still one failure mode left that causes de-sync. It happens > > when the else branch in alps_handle_interleaved_ps2 gets called more > > than once, i.e. we're accidentially reconstructing a 12-, 15- etc byte > > packet. This was easier to deal with in my first patch, I just > > collected the whole 9 bytes in a buffer and implicitly knew when the > > packet was over. Example of this happening: > > > > Dec 4 21:03:22 sardelle kernel: [410740.786121] alps.c: handle: cf > > Dec 4 21:03:22 sardelle kernel: [410740.787499] alps.c: handle: 79 > > Dec 4 21:03:22 sardelle kernel: [410740.788688] alps.c: handle: 12 > > Dec 4 21:03:22 sardelle kernel: [410740.789979] alps.c: handle: 1f > > Dec 4 21:03:22 sardelle kernel: [410740.791146] alps.c: handle: ff > > Dec 4 21:03:22 sardelle kernel: [410740.792299] alps.c: handle: 1 > > <suspect 9byte (really is)> > > Dec 4 21:03:22 sardelle kernel: [410740.796899] alps.c: handle: 4f > > <yup, it is, fold back> > > Ah, ok, so when we report all 3 buttons pressed we mistaken it as interleaved > packet again... Insteado f waiting till 9th byte can't we just forcefully > exit inetrleaved mode (once we processed the bare packet) by doing: > > psmouse->packet[3] &= 0xf7; Hmm I guess we could do something like this, but IMHO it makes the code needlessly arcane. What would be the point? Save 3 bytes of buffer? Deliver the mouse movement a microsecond earlier? Given that the interleaved packet is somehow a coherent piece of data sent by the touchpad, I'd store it exactly like that. Greetings! -- Sebastian Kapfer Inst. für Theoretische Physik I Office +49-9131-85-2-8450 Universität Erlangen Mobile +49-160-9577-6436 Staudtstr. 7, Raum 02.583. sebastian.kapfer@xxxxxxxxxxxxxxxxxxxxxx -- 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
