diff options
| author | Benjamin Tissoires <benjamin.tissoires@redhat.com> | 2022-02-03 15:32:26 +0100 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2022-03-01 15:46:03 +0100 |
| commit | 42764f97e6ebf1ff518c83e4a36395fddf7a6085 (patch) | |
| tree | 5acb6267b649b390af18c89979532166cf8283b0 /Documentation/input | |
| parent | 5c20000a4756f57c824e3045c978ef19136a676d (diff) | |
| download | lwn-42764f97e6ebf1ff518c83e4a36395fddf7a6085.tar.gz lwn-42764f97e6ebf1ff518c83e4a36395fddf7a6085.zip | |
Input: docs: add more details on the use of BTN_TOOL
The HID core stack used to be very relaxed considering the BTN_TOOL_*
usage. With the recent commits, we should now enforce to have only one
tool at a time, meaning that we can now express that requirement in the
docs.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Ping Cheng <ping.cheng@wacom.com>
Acked-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'Documentation/input')
| -rw-r--r-- | Documentation/input/event-codes.rst | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/Documentation/input/event-codes.rst b/Documentation/input/event-codes.rst index b24ae7d292cc..8741d390b184 100644 --- a/Documentation/input/event-codes.rst +++ b/Documentation/input/event-codes.rst @@ -137,7 +137,11 @@ A few EV_KEY codes have special meanings: code should be set to a value of 1. When the tool is no longer interacting with the input device, the BTN_TOOL_<name> code should be reset to 0. All trackpads, tablets, and touchscreens should use at least one BTN_TOOL_<name> - code when events are generated. + code when events are generated. Likewise all trackpads, tablets, and + touchscreens should export only one BTN_TOOL_<name> at a time. To not break + existing userspace, it is recommended to not switch tool in one EV_SYN frame + but first emitting the old BTN_TOOL_<name> at 0, then emit one SYN_REPORT + and then set the new BTN_TOOL_<name> at 1. * BTN_TOUCH: |