linux/drivers/hid
David Herrmann 6ce901eb61 HID: input: fix confusion on conflicting mappings
On an PC-101/103/104 keyboard (American layout) the 'Enter' key and its
neighbours look like this:

           +---+ +---+ +-------+
           | 1 | | 2 | |   5   |
           +---+ +---+ +-------+
             +---+ +-----------+
             | 3 | |     4     |
             +---+ +-----------+

On a PC-102/105 keyboard (European layout) it looks like this:

           +---+ +---+ +-------+
           | 1 | | 2 | |       |
           +---+ +---+ +-+  4  |
             +---+ +---+ |     |
             | 3 | | 5 | |     |
             +---+ +---+ +-----+

(Note that the number of keys is the same, but key '5' is moved down and
 the shape of key '4' is changed. Keys '1' to '3' are exactly the same.)

The keys 1-4 report the same scan-code in HID in both layouts, even though
the keysym they produce is usually different depending on the XKB-keymap
used by user-space.
However, key '5' (US 'backslash'/'pipe') reports 0x31 for the upper layout
and 0x32 for the lower layout, as defined by the HID spec. This is highly
confusing as the linux-input API uses a single keycode for both.

So far, this was never a problem as there never has been a keyboard with
both of those keys present at the same time. It would have to look
something like this:

           +---+ +---+ +-------+
           | 1 | | 2 | |  x31  |
           +---+ +---+ +-------+
             +---+ +---+ +-----+
             | 3 | |x32| |  4  |
             +---+ +---+ +-----+

HID can represent such a keyboard, but the linux-input API cannot.
Furthermore, any user-space mapping would be confused by this and,
luckily, no-one ever produced such hardware.

Now, the HID input layer fixed this mess by mapping both 0x31 and 0x32 to
the same keycode (KEY_BACKSLASH==0x2b). As only one of both physical keys
is present on a hardware, this works just fine.

Lets introduce hardware-vendors into this:
------------------------------------------

Unfortunately, it seems way to expensive to produce a different device for
American and European layouts. Therefore, hardware-vendors put both keys,
(0x31 and 0x32) on the same keyboard, but only one of them is hooked up
to the physical button, the other one is 'dead'.
This means, they can use the same hardware, with a different button-layout
and automatically produce the correct HID events for American *and*
European layouts. This is unproblematic for normal keyboards, as the
'dead' key will never report any KEY-DOWN events. But RollOver keyboards
send the whole matrix on each key-event, allowing n-key roll-over mode.
This means, we get a 0x31 and 0x32 event on each key-press. One of them
will always be 0, the other reports the real state. As we map both to the
same keycode, we will get spurious key-events, even though the real
key-state never changed.

The easiest way would be to blacklist 'dead' keys and never handle those.
We could simply read the 'country' tag of USB devices and blacklist either
key according to the layout. But... hardware vendors... want the same
device for all countries and thus many of them set 'country' to 0 for all
devices. Meh..

So we have to deal with this properly. As we cannot know which of the keys
is 'dead', we either need a heuristic and track those keys, or we simply
make use of our value-tracking for HID fields. We simply ignore HID events
for absolute data if the data didn't change. As HID tracks events on the
HID level, we haven't done the keycode translation, yet. Therefore, the
'dead' key is tracked independently of the real key, therefore, any events
on it will be ignored.

This patch simply discards any HID events for absolute data if it didn't
change compared to the last report. We need to ignore relative and
buffered-byte reports for obvious reasons. But those cannot be affected by
this bug, so we're fine.

Preferably, we'd do this filtering on the HID-core level. But this might
break a lot of custom drivers, if they do not follow the HID specs.
Therefore, we do this late in hid-input just before we inject it into the
input layer (which does the exact same filtering, but on the keycode
level).

If this turns out to break some devices, we might have to limit filtering
to EV_KEY events. But lets try to do the Right Thing first, and properly
filter any absolute data that didn't change.

This patch is tagged for 'stable' as it fixes a lot of n-key RollOver
hardware. We might wanna wait with backporting for a while, before we know
it doesn't break anything else, though.

Cc: <stable@vger.kernel.org>
Reported-by: Adam Goode <adam@spicenitz.org>
Reported-by: Fredrik Hallenberg <megahallon@gmail.com>
Tested-by: Fredrik Hallenberg <megahallon@gmail.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2015-01-06 22:18:13 +01:00
..
i2c-hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2014-12-12 10:26:47 -08:00
usbhid Merge branches 'for-3.19/hid-report-len', 'for-3.19/i2c-hid', 'for-3.19/lenovo', 'for-3.19/logitech', 'for-3.19/microsoft', 'for-3.19/plantronics', 'for-3.19/rmi', 'for-3.19/sony' and 'for-3.19/wacom' into for-linus 2014-12-12 11:15:33 +01:00
hid-a4tech.c HID: trivial devm conversion for special hid drivers 2013-07-31 10:12:28 +02:00
hid-apple.c HID: apple: add Apple wireless keyboard 2011 JIS model support 2014-02-06 14:35:18 +01:00
hid-appleir.c HID: appleir: force input to be set 2013-11-21 09:58:19 +01:00
hid-aureal.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-axff.c HID: enable Mayflash USB Gamecube Adapter 2013-11-12 19:06:23 +01:00
hid-belkin.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-cherry.c HID: fix a couple of off-by-ones 2014-08-21 10:43:28 -05:00
hid-chicony.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-core.c Merge branches 'for-3.19/hid-report-len', 'for-3.19/i2c-hid', 'for-3.19/lenovo', 'for-3.19/logitech', 'for-3.19/microsoft', 'for-3.19/plantronics', 'for-3.19/rmi', 'for-3.19/sony' and 'for-3.19/wacom' into for-linus 2014-12-12 11:15:33 +01:00
hid-cp2112.c driver:gpio remove all usage of gpio_remove retval in driver 2014-09-18 11:03:10 -07:00
hid-cypress.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-debug.c HID: add keyboard input assist hid usages 2014-10-20 21:03:58 +02:00
hid-dr.c HID: use hid_hw_request() instead of direct call to usbhid 2013-02-25 13:26:41 +01:00
hid-elecom.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-elo.c HID: hid-elo: some systems cannot stomach work around 2013-09-25 11:28:50 +02:00
hid-emsff.c HID: use hid_hw_request() instead of direct call to usbhid 2013-02-25 13:26:41 +01:00
hid-ezkey.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-gaff.c HID: use hid_hw_request() instead of direct call to usbhid 2013-02-25 13:26:41 +01:00
hid-generic.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-gt683r.c HID: gt683r: move mode attribute to led-class devices 2014-07-03 11:14:11 -07:00
hid-gyration.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-holtek-kbd.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-holtek-mouse.c HID: Add Holtek USB ID 04d9:a0c2 ETEKCITY Scroll 2014-09-08 09:48:56 +02:00
hid-holtekff.c HID: hid-holtekff: don't push static constants on stack for %*ph 2013-08-05 11:29:57 +02:00
hid-huion.c HID: huion: Use allocated buffer for DMA 2014-08-12 12:44:59 +02:00
hid-hyperv.c HID: hyperv: register as a wakeup source 2014-08-04 11:20:20 +02:00
hid-icade.c HID: icade: u16 which never < 0 2013-04-24 16:32:27 +02:00
hid-ids.h Merge branches 'for-3.19/hid-report-len', 'for-3.19/i2c-hid', 'for-3.19/lenovo', 'for-3.19/logitech', 'for-3.19/microsoft', 'for-3.19/plantronics', 'for-3.19/rmi', 'for-3.19/sony' and 'for-3.19/wacom' into for-linus 2014-12-12 11:15:33 +01:00
hid-input.c HID: input: fix confusion on conflicting mappings 2015-01-06 22:18:13 +01:00
hid-kensington.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-keytouch.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-kye.c HID: fix a couple of off-by-ones 2014-08-21 10:43:28 -05:00
hid-lcpower.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-lenovo.c HID: lenovo: Don't set EV_REP to avoid repeating mice buttons 2014-11-11 11:46:33 +01:00
hid-lg2ff.c HID: logitech - lg2ff: Add IDs for Formula Vibration Feedback Wheel 2013-10-09 12:06:02 +02:00
hid-lg3ff.c HID: LG: validate HID output report details 2013-09-13 15:12:39 +02:00
hid-lg4ff.c HID: logitech: Prevent possibility of infinite loop when using /sys interface 2014-08-15 10:54:13 +02:00
hid-lg.c HID: fix a couple of off-by-ones 2014-08-21 10:43:28 -05:00
hid-lg.h HID: hid-lg4ff: Adjust X axis input value accordingly to selected range. 2012-09-25 15:41:02 +02:00
hid-lgff.c HID: LG: validate HID output report details 2013-09-13 15:12:39 +02:00
hid-logitech-dj.c HID: logitech-dj: enable notifications on connect/disconnect 2014-10-29 10:51:40 +01:00
hid-logitech-hidpp.c HID: logitech-hidpp: disable io in probe error path 2014-12-11 23:10:01 +01:00
hid-magicmouse.c HID: magicmouse: sanity check report size in raw_event() callback 2014-08-27 09:14:39 +02:00
hid-microsoft.c HID: add support for MS Surface Pro 3 Type Cover 2014-11-11 11:39:32 +01:00
hid-monterey.c HID: fix a couple of off-by-ones 2014-08-21 10:43:28 -05:00
hid-multitouch.c HID: make hid_report_len as a static inline function in hid.h 2014-12-01 21:34:17 +01:00
hid-ntrig.c HID: ntrig: validate feature report details 2013-09-04 12:00:23 +02:00
hid-ortek.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-penmount.c HID: add support for PenMount HID TouchScreen Driver 2014-09-04 11:23:51 +02:00
hid-petalynx.c HID: fix a couple of off-by-ones 2014-08-21 10:43:28 -05:00
hid-picolcd_backlight.c HID: use hid_hw_request() instead of direct call to usbhid 2013-02-25 13:26:41 +01:00
hid-picolcd_cir.c [media] rc-core: remove protocol arrays 2014-07-25 19:10:43 -03:00
hid-picolcd_core.c HID: picolcd: be more verbose when reporting report size error 2014-08-27 23:27:10 +02:00
hid-picolcd_debugfs.c HID: picolcd: remove unnecessary NULL test before debugfs_remove 2014-06-30 09:54:22 +02:00
hid-picolcd_fb.c drivers/hid/hid-picolcd_fb: avoid world-writable sysfs files. 2014-05-14 10:53:56 +09:30
hid-picolcd_lcd.c HID: use hid_hw_request() instead of direct call to usbhid 2013-02-25 13:26:41 +01:00
hid-picolcd_leds.c HID: use hid_hw_request() instead of direct call to usbhid 2013-02-25 13:26:41 +01:00
hid-picolcd.h Merge branches 'for-3.10/multitouch', 'for-3.10/roccat' and 'for-3.10/upstream' into for-linus 2013-04-30 10:19:07 +02:00
hid-pl.c HID: pantherlord: validate output report details 2013-09-04 11:58:32 +02:00
hid-plantronics.c HID: plantronics: remove superfluous .probe() 2014-11-03 14:19:14 +01:00
hid-primax.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-prodikeys.c HID: prodikeys: Convert to snd_card_new() with a device pointer 2014-02-14 08:14:09 +01:00
hid-rmi.c HID: rmi: The address of query8 must be calculated based on which query registers are present 2014-12-12 11:14:55 +01:00
hid-roccat-arvo.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2013-09-06 09:30:36 -07:00
hid-roccat-arvo.h
hid-roccat-common.c HID: roccat: generalize some common code 2013-10-30 14:17:31 +01:00
hid-roccat-common.h HID: roccat: generalize some common code 2013-10-30 14:17:31 +01:00
hid-roccat-isku.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2013-09-06 09:30:36 -07:00
hid-roccat-isku.h HID: roccat: add support for IskuFX 2013-03-14 11:50:49 +01:00
hid-roccat-kone.c HID: roccat: Fix code style issues 2014-10-29 14:56:30 +01:00
hid-roccat-kone.h HID: roccat: added media key support for Kone 2013-04-08 10:33:13 +02:00
hid-roccat-koneplus.c HID: roccat: Fix "cannot create duplicate filename" problems 2013-09-30 10:51:31 +02:00
hid-roccat-koneplus.h HID: roccat: fix wrong attr size for koneplus tcu 2012-11-18 22:58:28 +01:00
hid-roccat-konepure.c HID: roccat: generalize some common code 2013-10-30 14:17:31 +01:00
hid-roccat-kovaplus.c HID: roccat: fix Coverity CID 141438 2013-11-04 10:55:20 +01:00
hid-roccat-kovaplus.h HID: roccat: deprecate some Kovaplus attributes 2012-11-12 15:30:29 +01:00
hid-roccat-lua.c HID: roccat: Drop cast 2014-06-27 00:33:44 +02:00
hid-roccat-lua.h HID: roccat: add support for Roccat Lua 2012-10-17 10:44:47 +02:00
hid-roccat-pyra.c HID: roccat: Fix "cannot create duplicate filename" problems 2013-09-30 10:51:31 +02:00
hid-roccat-pyra.h HID: roccat: deprecated some Pyra attributes 2012-11-12 15:30:28 +01:00
hid-roccat-ryos.c HID: roccat: add support for Ryos MK keyboards 2013-10-30 14:17:31 +01:00
hid-roccat-savu.c HID: roccat: generalize some common code 2013-10-30 14:17:31 +01:00
hid-roccat-savu.h HID: roccat: generalize some common code 2013-10-30 14:17:31 +01:00
hid-roccat.c HID: roccat: check cdev_add return value 2013-06-18 11:00:36 +02:00
hid-saitek.c HID: saitek: quirk for Saitek R.A.T.7 works with R.A.T.9 too 2014-11-05 15:13:59 +01:00
hid-samsung.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-sensor-hub.c HID: hid-sensor-hub: Use mfd_add_hotplug_devices() helper 2014-11-25 16:18:42 +00:00
hid-sjoy.c HID: use hid_hw_request() instead of direct call to usbhid 2013-02-25 13:26:41 +01:00
hid-sony.c HID: sony: Add support for the third-party SMK PS3 Bluetooth Remote 2014-11-20 15:05:27 +01:00
hid-speedlink.c HID: Fix Speedlink VAD Cezanne support for some devices 2013-08-26 13:51:10 +02:00
hid-steelseries.c HID: steelseries: validate output report details 2013-09-13 15:12:28 +02:00
hid-sunplus.c HID: fix a couple of off-by-ones 2014-08-21 10:43:28 -05:00
hid-thingm.c Merge branches 'for-3.18/always-poll-quirk', 'for-3.18/logitech', 'for-3.18/picolcd', 'for-3.18/rmi', 'for-3.18/sony', 'for-3.18/uhid', 'for-3.18/upstream' and 'for-3.18/wacom' into for-linus 2014-10-06 23:34:40 +02:00
hid-tivo.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-tmff.c HID: use hid_hw_request() instead of direct call to usbhid 2013-02-25 13:26:41 +01:00
hid-topseed.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-twinhan.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-uclogic.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-waltop.c HID: Use module_hid_driver macro 2013-01-03 10:27:31 +01:00
hid-wiimote-core.c HID: wiimote: replace hid_output_raw_report with hid_hw_output_report for output requests 2014-02-17 14:57:17 +01:00
hid-wiimote-debug.c HID: wiimote: fix DRM debug-attr to correctly parse input 2013-06-03 11:07:06 +02:00
hid-wiimote-modules.c HID: wiimote: add pro-controller analog stick calibration 2013-10-30 14:13:29 +01:00
hid-wiimote.h Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2013-11-15 16:48:22 -08:00
hid-xinmo.c HID: use module_hid_driver() to simplify the code 2013-08-26 13:23:04 +02:00
hid-zpff.c HID: zeroplus: validate output report details 2013-09-13 15:11:34 +02:00
hid-zydacron.c HID: trivial devm conversion for special hid drivers 2013-07-31 10:12:28 +02:00
hidraw.c Merge branch 'for-3.15/hid-core-ll-transport-cleanup' into for-linus 2014-04-01 19:05:09 +02:00
Kconfig Merge branches 'for-3.19/hid-report-len', 'for-3.19/i2c-hid', 'for-3.19/lenovo', 'for-3.19/logitech', 'for-3.19/microsoft', 'for-3.19/plantronics', 'for-3.19/rmi', 'for-3.19/sony' and 'for-3.19/wacom' into for-linus 2014-12-12 11:15:33 +01:00
Makefile Merge branches 'for-3.19/hid-report-len', 'for-3.19/i2c-hid', 'for-3.19/lenovo', 'for-3.19/logitech', 'for-3.19/microsoft', 'for-3.19/plantronics', 'for-3.19/rmi', 'for-3.19/sony' and 'for-3.19/wacom' into for-linus 2014-12-12 11:15:33 +01:00
uhid.c HID: uHID: fix excepted report type 2014-10-01 20:58:46 +02:00
wacom_sys.c Merge branches 'for-3.19/hid-report-len', 'for-3.19/i2c-hid', 'for-3.19/lenovo', 'for-3.19/logitech', 'for-3.19/microsoft', 'for-3.19/plantronics', 'for-3.19/rmi', 'for-3.19/sony' and 'for-3.19/wacom' into for-linus 2014-12-12 11:15:33 +01:00
wacom_wac.c Merge branches 'for-3.19/hid-report-len', 'for-3.19/i2c-hid', 'for-3.19/lenovo', 'for-3.19/logitech', 'for-3.19/microsoft', 'for-3.19/plantronics', 'for-3.19/rmi', 'for-3.19/sony' and 'for-3.19/wacom' into for-linus 2014-12-12 11:15:33 +01:00
wacom_wac.h HID: wacom: Report input events for each finger on generic devices 2014-12-11 23:01:56 +01:00
wacom.h HID: wacom - Bamboo pen-only tablet does not support PAD 2014-11-20 17:28:43 +01:00