On Jan 06 2017 or thereabouts, Peter Hutterer wrote: > On Wed, Jan 04, 2017 at 10:27:15AM +0100, Benjamin Tissoires wrote: > > On Jan 04 2017 or thereabouts, Peter Hutterer wrote: > > > On Tue, Jan 03, 2017 at 02:33:36PM -0800, Ping Cheng wrote: > > > > Hi Dmitry, > > > > > > > > On Tue, Jan 3, 2017 at 1:30 AM, Benjamin Tissoires > > > > <benjamin.tissoires@xxxxxxxxxx> wrote: > > > > > On Dec 22 2016 or thereabouts, 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@xxxxxxxxx> > > > > >> > > --- > > > > >> > > 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. > > > > > > > > By "to interrogate the device again", do you mean once we report > > > > EV_SYN/SYN_CONFIG, userspace needs to reinitialize the device? > > > > > > > > If not, how do we tell userspace which feature/info has been changed? > > > > > > > > >> > > > > >> Benjamin, Peter, any opinion on the above? > > > > > > > > > > Oooh, so that's the purpose of this event :) (the documentation says > > > > > "TBD"). I am fine with that. We would need to adapt the documentation in > > > > > Documentation/input/event-codes.txt and make sure the handlers are > > > > > properly adapted too (*maybe* add a SYN_DROP event to empty the queue of > > > > > the events in userspace). > > > > > > > > Can you update the "TBD" in Documentation/input/event-codes.txt so we > > > > have an agreed description to follow? > > > > > > Here's a first attempt: > > > > > > * SYN_CONFIG: > > > - Used to indicate that the device's static description has changed. This > > > > Should we indicate the obvious fact that this is only after the device has > > been registered and presented to userspace? I can imagine drivers adding > > those notifications after each declaration while preparing the input > > node :) > > added, see below > > > > > > can happen when > > > - at least one event type or code has been added or removed, or > > > - at least one device property has been added or removed, or > > > - at least one absolute axis has changed properties, or > > > - the keycode has changed, or > > > - the name, id, phys or unique identifier of the device has changed, > > > A client should re-query the device once a SYN_CONFIG has been received > > > as if the device was newly added. SYN_CONFIG does not indicate which > > > information changed, a client is required to re-read the full > > > state. A SYN_CONFIG may be triggered even by types/codes/... that the > > > client is not aware of, i.e. the state before and after may look > > > identical to any given client. > > > Dynamic values such as key state, switch state, absolute axis value, > > > force feedback, etc. do not trigger a SYN_CONFIG. A SYN_CONFIG may > > > trigger a SYN_DROPPED to terminate ongoing event sequences. > > > > I think we should enforce this last sentence a little bit more: > > "A SYN_CONFIG is basically a reset of the device so it should be > > considered as a SYN_DROPPED from the client perspective. For backward > > compatibility with clients not supporting SYN_CONFIG, a SYN_DROPPED > > event is sent right before SYN_CONFIG." > > Are we planning to force a SYN_DROPPED every time? Even when the event queue > is empty? I think it wouldn't do much other than keep the client busy. > > Come to think of it, there's a chance that this *reduces* backwards > compatibility. Until a SYN_DROPPED occurs, a client has no reason to ever > check bits again. But re-fetching all states during SYN_DROPPED is normal, > so if one axis disappears, the client may now get confused. Ouch, very much ouch. Maybe SYN_CONFIG should be limited to only props, axis ranges and new axis? > > > Also, maybe we should add a warning about the udev properties: > > "If a SYN_CONFIG allows to change the static description of a device, it > > should be used with care. Some userspace pieces (udev) rely on the > > device creation to tag it properly. Completely changing the device type > > from a mouse to a touchpad is better handled through the destruction and > > then creation of a new input node than relying on SYN_CONFIG" > > > > (please fix typos/grammar/jibberish) > > > > > > > > We should also add a blurb to the EVIOC*MASK ioctls about SYN_CONFIG. > > > > Saying that it can't be masked and that it will invalidate the current > > masks? Or this is the responsibility of the client? > > I would just leave the masks as-is, less work and more predictability. This > means that a client has to re-apply them on SYN_CONFIG to avoid events from > new axes (if any) but that seems like the most straightforward approach. We > already allow masking out axes a device doesn't have, so invalidating > doesn't really give us any benefits. > > Ok, let's have a v2 draft: > > * SYN_CONFIG: > - Used to indicate that the device's static description has changed, after > the device has been registered and presented to userspace. > This can happen when > - at least one event type or code has been added or removed, or > - at least one device property has been added or removed, or > - at least one absolute axis has changed properties, or > - the keycode has changed, or > - the name, id, phys or unique identifier of the device has changed, > Do not send this event during the initial device initialization process, > this event is exclusively for changes at runtime. > > A client should re-query the device once a SYN_CONFIG has been received > as if the device was newly added. SYN_CONFIG does not indicate which > information changed, a client is required to re-read the full > state. A SYN_CONFIG may be triggered even by types/codes/... that the > client is not aware of, i.e. the state before and after may look > identical to any given client. > > Dynamic values such as key state, switch state, absolute axis value, > force feedback, etc. do not trigger a SYN_CONFIG. A SYN_CONFIG may > trigger a SYN_DROPPED to terminate ongoing event sequences. > > SYN_CONFIG should be used with extreme care. There is no guarantee that > a SYN_CONFIG event is handled correctly by a client, or even noticed. > For example, udev relies on the original device description only to > assign a device type. If a SYN_CONFIG were to change the device > sufficiently to warrant a new device type tag, this may never be > detected. Changing a device type (e.g. from mouse to touchpad) is better > handled through the destruction and recreation of the input node. I like it. Besides the legacy breakage we are talking about above. Cheers, Benjamin > > Cheers, > Peter > -- 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
