On Thu, Feb 03, 2022 at 03:32:26PM +0100, Benjamin Tissoires wrote: > 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> > > --- > > changes in v2: > - changed to explain that switching tool in one EV_SYN report > is not nice for userspace > --- > Documentation/input/event-codes.rst | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > 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 I still think s/export/set to nonzero/ to avoid any ambiguity with setting the evbit on the device vs setting the value to nonzero here, but the remainder is good, thanks :) Acked-by: Peter Hutterer <peter.hutterer@xxxxxxxxx> Cheers, Peter > + 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: > > -- > 2.33.1 >
