Re: [PATCH 3/3] goldfish: multitouch: no extra EV_SYN

[Alan Cox <alan@linux.intel.com>]

> >  	input_event(edev->input, type, code, value);
> > -	input_sync(edev->input);
> > +	/*
> > +	 * Send an extra (EV_SYN, SYN_REPORT, 0x0) event
> > +	 * if a key was pressed. Some keyboard device
> > +	 * drivers may only send the EV_KEY event and
> > +	 * not EV_SYN.
> 
> That would be error in that keyboard driver and should be fixed.

Agreed but it's still the case that current and long standing Goldfish
behaviour requires the above.

> > +	 * Note that sending an extra SYN_REPORT is not
> > +	 * necessary nor correct protocol with other
> > +	 * devices such as touchscreens, which will send
> > +	 * their own SYN_REPORT's when sufficient event
> > +	 * information has been collected (e.g., for
> > +	 * touchscreens, when pressure and X/Y coordinates
> > +	 * have been received). Hence, we will only send
> > +	 * this extra SYN_REPORT if type == EV_KEY.
> > +	 */
> > +	if (type == EV_KEY)
> > +		input_sync(edev->input);
> 
> 
> I'd rather we always rely on the host to send the SYN event.

That would certainly make sense for the future.

> > +
> >  	return IRQ_HANDLED;
> >  }
> >  
> > @@ -154,6 +173,15 @@ static int events_probe(struct platform_device
> > *pdev)
> >  
> >  	input_dev->name = edev->name;
> >  	input_dev->id.bustype = BUS_HOST;
> > +	/*
> > +	 * Set the Goldfish Device to be multi-touch.
> > +	 * If we do not issue input_mt_init_slots,
> > +	 * the kernel will filter out needed ABS_MT_SLOT
> > +	 * events when we touch the screen in more than one place,
> > +	 * preventing multi-touch with more than one finger from
> > working.
> > +	 * See drivers/input/input.c:input_handle_abs_event.
> > +	 */
> > +	input_mt_init_slots(input_dev, GOLDFISH_MAX_FINGERS, 0);
> 
> Can we use data retrieved by events_import_abs_params() to set up
> correct number of slots? Also we need error handling. And possibly
> retrieve correct properties to set pass to input_mt_init_slots()...

Again - I agree that makes sense for future versions of Goldfish

Alan