Re: [PATCH v3] HID: wacom: generic: add 5 tablet touch keys

[Peter Hutterer <peter.hutterer@who-t.net>]

On Thu, Dec 22, 2016 at 05:13:23PM -0800, Dmitry Torokhov wrote:
> On Mon, Dec 19, 2016 at 11:30:13AM +0100, Jiri Kosina wrote:
> > On Fri, 16 Dec 2016, Ping Cheng wrote:
> > 
> > > Wacom Cintiq Pro [1] is a series of display tablets. They support
> > > 5 touch keys on the tablet. Those keys represent specific functions.
> > > They turn display off; bring up OSD; bring up On Screen Keyboard;
> > > bring up desktop control panel; and turn touch on/off.
> > > 
> > > The most left touch key, that turns display on/off, is controlled by
> > > firmware. When the display is on, the mode is set. Otherwise, the
> > > mode is off. So, it works like a switch. That's why we introduced a
> > > new switch: SW_INDIRECT. The switch defauts to INDIRECT instead of DIRECT
> > > was a request from useland, more specifically Gnome, developers.
> > > 
> > > Other four touch keys are true software keys. We use the existing
> > > KEY_BUTTONCONFIG and KEY_CONTROLPANEL for OSD and control panel. But,
> > > we have to request two new keys: KEY_ONSCREEN_KEYBOARD and KEY_MUTE_DEVICE
> > > since none of the existing keys support those two actions.
> > > 
> > > [1] http://www.wacom.com/en-us/products/pen-displays/wacom-cintiq-pro
> > > 
> > > Signed-off-by: Ping Cheng <ping.cheng@wacom.com>
> > > ---
> > > v3: Since no one has followed up with v2, let's add some more comments for
> > > SW_INDIRECT so we keep the offlist decision public ;).
> > 
> > [ ... snip ... ]
> > 
> > > diff --git a/include/uapi/linux/input-event-codes.h b/include/uapi/linux/input-event-codes.h
> > > index d6d071f..32ef894 100644
> > > --- a/include/uapi/linux/input-event-codes.h
> > > +++ b/include/uapi/linux/input-event-codes.h
> > > @@ -641,6 +641,9 @@
> > >   * e.g. teletext or data broadcast application (MHEG, MHP, HbbTV, etc.)
> > >   */
> > >  #define KEY_DATA			0x275
> > > +/* same as SW_MUTE_DEVICE but triggered by a key */
> > > +#define KEY_MUTE_DEVICE 		0x278
> > > +#define KEY_ONSCREEN_KEYBOARD		0x279
> > >  
> > >  #define BTN_TRIGGER_HAPPY		0x2c0
> > >  #define BTN_TRIGGER_HAPPY1		0x2c0
> > > @@ -781,7 +784,8 @@
> > >  #define SW_LINEIN_INSERT	0x0d  /* set = inserted */
> > >  #define SW_MUTE_DEVICE		0x0e  /* set = device disabled */
> > >  #define SW_PEN_INSERTED		0x0f  /* set = pen inserted */
> > > -#define SW_MAX			0x0f
> > > +#define SW_INDIRECT		0x10  /* set = not a direct input device */
> > > +#define SW_MAX			0x1f
> > 
> > I'd like to have explicit Ack from Dmitry on these ... Dmitry?
> 
> Sorry for the delay, but I think adding SW_INDIRECT is actually wrong.
> 
> What Wacom folks seem to need is way to re-classfiy the device (i.e.
> update its properties) and let userspace know somehow. We can't keep
> adding SW_INDIRECT and SW_NOTPOINTER and SW_NOTBUTTONPAD and so forth.
> We however have EV_SYN/SYN_CONFIG that we may use to let userspace know
> that device configuration changed and that userspace needs to
> interrogate the device again. We can emit this code both when we change
> properties as well as when we change ABS limits and changing keymaps and
> so forth.
> 
> Benjamin, Peter, any opinion on the above?

hmm, I quite like the idea. provided we can define the semantics correctly
(mostly to figure out what happens with ongoing events during SYN_CONFIG)
this should work, at least for new clients.

Existing clients will largely treat SYN_CONFIG as noop or like SYN_REPORT.

Cheers,
   Peter

> 
> I'm OK with the other 2 new keycodes.
> 
> Thanks.
> 
> -- 
> Dmitry