Detect MSC_SCAN as a trigger where EV_KEY is absent

[uingitu]

Have you checked if an issue already exists for this feature request?

• Nobody else has requested this feature before

What feature would you like added?

Hi, thanks for a great app!

Would it be possible to be able to detect unknown buttons when recording a trigger similar to remap UNKNOWN buttons in tvQuickActions ? https://tvdevinfo.com/tvquickactions/howto/getevent/

This would allow to extend functionality especially on android tv by adding for example number or channel up/down buttons with a universal remote when the original remote does not have any.

App version

No response

Device model and manufacturer

No response

Extra info

• My device is rooted

[jambl3r]

This is easily solvable by us just supporting more event types. Key Mapper's Expert Mode is already doing essentially the same as what tvQuickActions does (which you should try if you haven't already). Currently we filter out certain event types and even whole devices to avoid accidentally preventing you from using your touch screen. We are investigating safe ways to relax those filters to let more events pass through.

Please refer to #2083 and if you know how to use adb and getevent you could provide output from your device to help us find the events that Expert Mode is not detecting as a trigger.

[uingitu]

Thank you for the quick response.

I had checked #2083 and I thought it was a more general description but now that I read it again it is exactly MSC_SCAN that maybe shouldn't be filtered out and allowed to remap it, even without expert mode if possible.

For example, on an Nvidia Shield 2015 16GB with built-in infrared receiver, the remote layout is https://www.nvidia.com/en-us/shield/support/shield-tv/know-your-shield-tv/#shieldremote and the following NEC IR codes are already supported https://nvidia.custhelp.com/app/answers/detail/a_id/4603/~/ir-codes-for-shield-tv

Keys	Address (hex)	Command (hex)
Vol up	0x807e	0x12	Vol up
Vol down	0x807e	0x15	Vol down
Up	0x807e	0x0c	Up
Down	0x807e	0x0e	Down
Left	0x807e	0x0b	Left
Right	0x807e	0x0d	Right
Select(OK)	0x807e	0x03	OK
Back	0x807e	0x02	Back
Home(Menu)	0x807e	0x09	Menu
POWER_Toggle	0x807e	0x06	POWER(toggle)
Mute/Unmute	0x807e	0x14	Mute
Play/Pause	0x807e	0x20	N/A
Play	0x8073	0x11	Play
Pause	0x807e	0x08	Pause
STOP	0x807e	0x07	STOP
FWD	0x807e	0x0f	FWD
RWD	0x807e	0x0a	RWD

Logs when pressing RWD (rewind) NEC IR command hex 0a or decimal 10 on the remote

adb shell getevent
add device 1: /dev/input/event5
  name:     "IPControl_UPnP_RemoteService"
add device 2: /dev/input/event4
  name:     "shield-ask-remote"
add device 3: /dev/input/event3
  name:     "virtual-search"
add device 4: /dev/input/event2
  name:     "tegra-hda HDMI/DP,pcm=3"
add device 5: /dev/input/event0
  name:     "gpio_ir_recv"
could not get driver version for /dev/input/mice, Inappropriate ioctl for device
add device 6: /dev/input/event1
  name:     "gpio-keys"
/dev/input/event0: 0004 0004 00807e0a
/dev/input/event0: 0001 00a8 00000001
/dev/input/event0: 0000 0000 00000000
/dev/input/event0: 0001 00a8 00000000
/dev/input/event0: 0000 0000 00000000

adb shell getevent -l
add device 1: /dev/input/event5
  name:     "IPControl_UPnP_RemoteService"
add device 2: /dev/input/event4
  name:     "shield-ask-remote"
add device 3: /dev/input/event3
  name:     "virtual-search"
add device 4: /dev/input/event2
  name:     "tegra-hda HDMI/DP,pcm=3"
add device 5: /dev/input/event0
  name:     "gpio_ir_recv"
add device 6: /dev/input/event1
  name:     "gpio-keys"
could not get driver version for /dev/input/mice, Inappropriate ioctl for device
/dev/input/event0: EV_MSC       MSC_SCAN             00807e0a
/dev/input/event0: EV_KEY       KEY_REWIND           DOWN
/dev/input/event0: EV_SYN       SYN_REPORT           00000000
/dev/input/event0: EV_KEY       KEY_REWIND           UP
/dev/input/event0: EV_SYN       SYN_REPORT           00000000

Keymapper detects it without expert mode as Rewind (gpio_ir_recv) and can be remapped.

Logs when pressing FWD (fast forward) NEC IR command hex 0f or decimal 15 on the remote

adb shell getevent
add device 1: /dev/input/event5
  name:     "IPControl_UPnP_RemoteService"
add device 2: /dev/input/event4
  name:     "shield-ask-remote"
add device 3: /dev/input/event3
  name:     "virtual-search"
add device 4: /dev/input/event2
  name:     "tegra-hda HDMI/DP,pcm=3"
could not get driver version for /dev/input/mice, Inappropriate ioctl for device
add device 5: /dev/input/event0
  name:     "gpio_ir_recv"
add device 6: /dev/input/event1
  name:     "gpio-keys"
/dev/input/event0: 0004 0004 00807e0f
/dev/input/event0: 0001 00d0 00000001
/dev/input/event0: 0000 0000 00000000
/dev/input/event0: 0001 00d0 00000000
/dev/input/event0: 0000 0000 00000000

adb shell getevent -l
add device 1: /dev/input/event5
  name:     "IPControl_UPnP_RemoteService"
add device 2: /dev/input/event4
  name:     "shield-ask-remote"
add device 3: /dev/input/event3
  name:     "virtual-search"
add device 4: /dev/input/event2
  name:     "tegra-hda HDMI/DP,pcm=3"
could not get driver version for /dev/input/mice, Inappropriate ioctl for device
add device 5: /dev/input/event0
  name:     "gpio_ir_recv"
add device 6: /dev/input/event1
  name:     "gpio-keys"
/dev/input/event0: EV_MSC       MSC_SCAN             00807e0f
/dev/input/event0: EV_KEY       KEY_FASTFORWARD      DOWN
/dev/input/event0: EV_SYN       SYN_REPORT           00000000
/dev/input/event0: EV_KEY       KEY_FASTFORWARD      UP
/dev/input/event0: EV_SYN       SYN_REPORT           00000000

Keymapper detects it without expert mode as Fast Forward (gpio_ir_recv) and can be remapped.

Using a universal remote and programming NEC IR protocol device 128 subdevice 126 the aforementioned codes https://nvidia.custhelp.com/app/answers/detail/a_id/4603/~/ir-codes-for-shield-tv work correctly because they are already defined in key layout file /system/usr/keylayout/Vendor_0955_Product_7217.kl https://source.android.com/docs/core/interaction/input/key-layout-files

# Copyright (c) 2019,2021 NVIDIA CORPORATION.  All rights reserved.

# NVIDIA Shield Remote (2019 edition)

key 116   POWER
# The menu button is mapped to menu by default
key 139   MENU

# (D-pad is reported as individual buttons.)
key 103   DPAD_UP
key 105   DPAD_LEFT
key 106   DPAD_RIGHT
key 108   DPAD_DOWN
key 353   DPAD_CENTER

key 158   BACK
key 172   HOME

key 217   ASSIST

key 114   VOLUME_DOWN
key 115   VOLUME_UP

key 208   MEDIA_FAST_FORWARD
key 164   MEDIA_PLAY_PAUSE
key 168   MEDIA_REWIND

# The netflix button is mapped to button_12
key 393   BUTTON_12

I would like to add number buttons for unused NEC1 IR codes for example decimal 200-209 for 0-9 which getevent detects but probalby because they are not defined in the key layout file, they are not detected when recording a trigger in keymapper.

When IR code hex c8 decimal 200 is sent, getevent logs

adb shell getevent
add device 1: /dev/input/event5
  name:     "IPControl_UPnP_RemoteService"
add device 2: /dev/input/event4
  name:     "shield-ask-remote"
add device 3: /dev/input/event3
  name:     "virtual-search"
add device 4: /dev/input/event2
  name:     "tegra-hda HDMI/DP,pcm=3"
could not get driver version for /dev/input/mice, Inappropriate ioctl for device
add device 5: /dev/input/event0
  name:     "gpio_ir_recv"
add device 6: /dev/input/event1
  name:     "gpio-keys"
/dev/input/event0: 0004 0004 00807ec8
/dev/input/event0: 0000 0000 00000000

adb shell getevent -l
add device 1: /dev/input/event5
  name:     "IPControl_UPnP_RemoteService"
add device 2: /dev/input/event4
  name:     "shield-ask-remote"
add device 3: /dev/input/event3
  name:     "virtual-search"
add device 4: /dev/input/event2
  name:     "tegra-hda HDMI/DP,pcm=3"
could not get driver version for /dev/input/mice, Inappropriate ioctl for device
add device 5: /dev/input/event0
  name:     "gpio_ir_recv"
add device 6: /dev/input/event1
  name:     "gpio-keys"
/dev/input/event0: EV_MSC       MSC_SCAN             00807ec8
/dev/input/event0: EV_SYN       SYN_REPORT           00000000

When IR code hex c9 decimal 201 is sent, getevent logs

adb shell getevent
add device 1: /dev/input/event5
  name:     "IPControl_UPnP_RemoteService"
add device 2: /dev/input/event4
  name:     "shield-ask-remote"
add device 3: /dev/input/event3
  name:     "virtual-search"
add device 4: /dev/input/event2
  name:     "tegra-hda HDMI/DP,pcm=3"
could not get driver version for /dev/input/mice, Inappropriate ioctl for device
add device 5: /dev/input/event0
  name:     "gpio_ir_recv"
add device 6: /dev/input/event1
  name:     "gpio-keys"
/dev/input/event0: 0004 0004 00807ec9
/dev/input/event0: 0000 0000 00000000

adb shell getevent -l
add device 1: /dev/input/event5
  name:     "IPControl_UPnP_RemoteService"
add device 2: /dev/input/event4
  name:     "shield-ask-remote"
add device 3: /dev/input/event3
  name:     "virtual-search"
add device 4: /dev/input/event2
  name:     "tegra-hda HDMI/DP,pcm=3"
add device 5: /dev/input/event0
  name:     "gpio_ir_recv"
could not get driver version for /dev/input/mice, Inappropriate ioctl for device
add device 6: /dev/input/event1
  name:     "gpio-keys"
/dev/input/event0: EV_MSC       MSC_SCAN             00807ec9
/dev/input/event0: EV_SYN       SYN_REPORT           00000000

The MSC_SCAN is the address 807e concatenated with the hex of the button pressed c8.

If keymapper allowed MSC_SCAN to be remapped when there is no EV_KEY defined and even better without expert mode, it would allow a lot more functionality.

[jambl3r]

Thank you for such a detailed analysis. This is amazingly helpful!

---

You would definitely need Expert Mode for this, MSC_SCAN is a little scancode on its own and is missing the key event so Android does nothing with it. You need to be down at this level to be able to detect it.

It's awkward because there is only one event on the down press, and no 'up' event. We have been anticipating to see this kind of thing, and there are already triggers in Key Mapper that have no concept of an 'up' event (Assistant trigger for example).

Some buttons will output MSC_SCAN and normal key events as well (you even have an example of this), which complicates things further, because what do you listen out for?

A way we could approach this is that, helpfully, incoming events arrive in little groups and are always accompanied with a SYN_REPORT. We could consider each of these groups as they come in and if there is a MSC_SCAN on its own with no key events, then it could be considered as a key press on its own, and treated like a down press immediately followed by an up press.

This would mean you cannot use long press with these kinds of triggers and we need a nice way to convey that to the user without burdening them with the details of why.

We also need to know if some devices will send a MSC_SCAN on key up, in which case, we have a problem that some devices behave one way and others a different way.

[jambl3r]

Making this its own issue because MSC_SCAN was previously off the table, but it needs considering in its own right

[uingitu]

Thanks again for taking the time to look into this.

Your proposed steps for handling EV_MSC without EV_KEY are probably the best solution so that it is transparent to the user.

For now, in order to be able to test it hopefully without major code restructuring and since this is an advanced use case for experienced users avoiding confusion for beginners, perhaps low level key detection could be enabled within expert mode setting using a toggle button with warning about possible non-uniqueness. After enabling it, when you record a new key, the record trigger could detect unmapped buttons while also disabling the long press option, making it grey.

Searching the issues using getevent as keyword, similar to this were #761 #1276 and #1564 so if this low level detection of EV_MSC without EV_KEY could be implemented, it would cover those use cases as well.