Re: [PATCH 0/2] Input: discard pre-registration events and test state seeding

[Karlos Abel <kabel@voidship.net>]

Resending in plain text; the mailing lists rejected my previous reply
because it contained HTML.

Hi Dmitry,

The observed problem is the initial switch event being delivered later and
undoing a subsequent Bluetooth soft-block. It does not depend on the event
timestamp.

hotkey_init() seeds SW_RFKILL_ALL=1 before registering the input device,
without calling input_sync(). That updates the switch state, but also
leaves the event queued across registration.

In the unpatched hardware trace:

At 74.486 seconds, Bluetooth is explicitly soft-blocked.
At 80.300 seconds, Xorg injects LED updates followed by SYN_REPORT. There
is already one event queued.
That flush delivers the old SW_RFKILL_ALL=1 to rfkill_event(), which
schedules a global unblock and turns Bluetooth back on.

rfkill_start() already reads the initial switch state when the handler
attaches; this later delivery produces an additional action after userspace
has changed the soft-block state.

Regarding the missing input_sync(): from reading the initialization path,
simply adding it alongside the seed would be ignored because EV_SYN is not
enabled on this device until input_register_device().

I targeted registration because input_event() documents pre-registration
seeding as updating initial state without delivering those events to
handlers. The patch retains that state while discarding the pending events.
The timestamp reset addresses a separate stale-timestamp case covered by
the tests.

Thanks very much,

Karlos


On Sun, Oct 11, 2026 at 12:45 AM Dmitry Torokhov <dmitry.torokhov@gmail.com>
wrote:

> Hi Karlos,
>
> On Sat, Oct 10, 2026 at 02:00:29PM -0400, Karlos Abel wrote:
> > This series prevents input handlers from receiving buffered
> initialization
> > events after device registration. On a ThinkPad T14 Gen 6, a later LED
> > update flushed a stale SW_RFKILL_ALL event seeded by thinkpad_acpi.
> > The fix drops the pending events and their timestamp before handlers
> > attach, while retaining the seeded switch and absolute-axis state.
>
> Could you explain why these seeded events give you trouble? Is it
> because thinkpad_acpi() forgets to send input_sync() and so the
> timestamp is stale/wrong?
>
> Thanks.
>
> --
> Dmitry
>