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@xxxxxxxxxx>
---
Documentation/input/event-codes.rst | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/Documentation/input/event-codes.rst b/Documentation/input/event-codes.rst
index b24ae7d292cc..41b1fa647dab 100644
--- a/Documentation/input/event-codes.rst
+++ b/Documentation/input/event-codes.rst
@@ -137,7 +137,10 @@ 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. It is
+ however accepted to switch tool in one EV_SYN frame by setting the old
+ BTN_TOOL_<name> at a value of 0 and the new one at 1.
* BTN_TOUCH:
--
2.33.1
