linux-kernel - [PATCH v5 0/3] TrackPoint doubletap enablement and user control

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Message-ID: <20251226235101.106451-1-vishnuocv@gmail.com>
Date: Sat, 27 Dec 2025 08:50:58 +0900
From: Vishnu Sankar <vishnuocv@...il.com>
To: dmitry.torokhov@...il.com,
	hmh@....eng.br,
	hansg@...nel.org,
	ilpo.jarvinen@...ux.intel.com,
	corbet@....net,
	derekjohn.clark@...il.com
Cc: mpearson-lenovo@...ebb.ca,
	linux-doc@...r.kernel.org,
	linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	ibm-acpi-devel@...ts.sourceforge.net,
	platform-driver-x86@...r.kernel.org,
	vsankar@...ovo.com,
	Vishnu Sankar <vishnuocv@...il.com>
Subject: [PATCH v5 0/3] TrackPoint doubletap enablement and user control

This patch series adds support for TrackPoint doubletap with a clear and
simple separation of responsibilities between drivers:

1. Firmware enablement (trackpoint.c):
   Automatically enables doubletap on capable hardware during device
   detection.

2. User control (thinkpad_acpi.c):
   Provides a sysfs interface to enable or disable delivery of doubletap
   events to userspace.

The approach follows the KISS principle:
- The TrackPoint driver enables hardware functionality by default.
- The thinkpad_acpi driver controls whether ACPI doubletap events are
  delivered, using existing hotkey filtering infrastructure.
- No cross-driver APIs or dual filtering paths are introduced.

Changes in v5:
- Rename sysfs attribute from doubletap_filter to doubletap_enable to
  reflect actual behavior.
- Fix inverted logic so events are delivered only when doubletap is
  enabled.
- Suppress ACPI hotkey delivery instead of injecting or filtering input
  events.
- Register the sysfs attribute via hotkey_attributes[] instead of
  device_create_file().
- Drop unnecessary helper wrappers and debug logging.
- Update Documentation to reflect the new naming and semantics.

Changes in v4:
- Complete redesign based on reviewer feedback.
- trackpoint.c: Simplified to only enable doubletap by default.
- trackpoint.c: Removed all sysfs attributes and global variables.
- trackpoint.c: Uses firmware ID detection with deny list.
- thinkpad_acpi.c: Added sysfs interface for kernel-level event control.
- thinkpad_acpi.c: No cross-driver dependencies.
- Documentation: Updated to reflect simplified sysfs approach.

Changes in v3:
- No changes.

Changes in v2:
- Improved commit messages.
- Removed unnecessary comments and debug messages.
- Switched to strstarts() usage.
- Simplified firmware capability detection logic.

This version addresses the remaining review feedback by correcting the
naming and logic inversion, aligning sysfs semantics with behavior, and
fully integrating with existing thinkpad_acpi hotkey handling.

Vishnu Sankar (3):
  input: trackpoint - Enable doubletap by default on capable devices
  platform/x86: thinkpad_acpi: Add sysfs control for TrackPoint
    double-tap
  Documentation: thinkpad-acpi - Document doubletap_enable attribute

 .../admin-guide/laptops/thinkpad-acpi.rst     | 20 ++++++++
 drivers/input/mouse/trackpoint.c              | 47 +++++++++++++++++++
 drivers/input/mouse/trackpoint.h              |  5 ++
 drivers/platform/x86/lenovo/thinkpad_acpi.c   | 42 ++++++++++++++---
 4 files changed, 107 insertions(+), 7 deletions(-)

-- 
2.51.0