Re: usbtouchscreen: Add support for Zytronic capacitive touchscreen

[Daniel Silverstone <dsilvers@simtec.co.uk>]

> > Index: linux.git/drivers/input/touchscreen/usbtouchscreen.c
> > +	/* Always service the USB devices irq not just when the input device is
> > +	 * open.
> > +	 */
> > +	int irq_always;
> > +
> Why is this needed?

Some devices (E.g. specifically this one) expect their interrupt
endpoints to always be serviced. In this case, the device has an
on-board watchdog and will reboot (disconnect and reconnecting to the
USB) if it is not serviced in a timely fashion.


> > +	case 0xC0: /* down */
> > +		dev->x = (pkt[1] & 0x7f) | ((pkt[2] & 0x07) << 7);
> > +		dev->y = (pkt[3] & 0x7f) | ((pkt[4] & 0x07) << 7);
> > +		dev->touch = 1;
> > +		dev->press = 1;
> Since the device does not report real pressure readings don't try to
> fake it, reporting touch is enough.

I believe that this is because some userland libraries, particularly
tslib, require the pressure reading in order to believe the device is
functioning usefully. Specifically, consider plugins/input-raw of
tslib's source package which uses pressure rather than touch.

Regards,

Daniel.

-- 
Daniel Silverstone                              http://www.simtec.co.uk/
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