Re: [PATCH v7 3/3] Input: add driver for the Hycon HY46XX touchpanel series

[Giulio Benetti]

Hi Peter, Dmitry,

On 4/14/21 8:46 AM, Peter Hutterer wrote:
> On Tue, Apr 13, 2021 at 10:44:07PM -0700, Dmitry Torokhov wrote:
> > Hi Giulio,
> >
> > On Tue, Apr 13, 2021 at 04:44:46PM +0200, Giulio Benetti wrote:
> > > +
> > > +	input_mt_report_pointer_emulation(tsdata->input, true);
> >
> > For touchscreens it does not make much sense to report BTN_DOUBLETAP,
> > BTN_TRIPLETAP, etc, events (they are really for touchpads), so I changed
> > this to
> >
> > 	input_mt_report_pointer_emulation(tsdata->input, false);
> >
> > to only report ABS_X, ABS_Y, and BTN_TOUCH, and applied.
>
> Can you expand on this please, just to make sure I'm not misinterpreting
> those codes? Those bits are just for how many fingers are down (but without
> position), dropping those bits means you restrict the device to a pure
> single-touch screen. Or am I missing something here?

I've re-tested the driver after setting 
input_mt_report_pointer_emulation() use_count to false. It works 
correctly with all touch points expected. That use_count refers to 
finger count of Touchpad[1]. Also you can see that even with 
use_count=false this for loop[2] is entered by counting all the 
mt->slots and then input_event() reports all of them.

I hope I've understood correctly :-)

[1]: 
https://elixir.bootlin.com/linux/v5.12-rc7/source/drivers/input/input-mt.c#L190
[2]: 
https://elixir.bootlin.com/linux/v5.12-rc7/source/drivers/input/input-mt.c#L208

> then again, MT support has been in the kernel for long enough that by now
> everything should understand it, so there's a certain "meh" factor.
>
> Cheers,
>     Peter

Best regards
--
Giulio Benetti
Benetti Engineering sas