[PATCH v2 0/3] Input: synaptics - enable SMBus for ThinkPad P14s Gen 2i (LEN2072)

[Dmitry Mikushin <dmitry@kernelgen.org>]

The ThinkPad P14s Gen 2i touchpad (Synaptics TM3471-030, LEN2072) is
not on the SMBus passlist and runs in PS/2 mode. Forcing RMI4 alone
does not help: the F12 attention handler reads the whole 79-byte data
packet over SMBus on every frame, which caps the report rate at about
43 Hz and loses fast swipes.

Patch 1 fixes the size passed to rmi_f12_process_objects(), which
counted from the start of the data packet instead of from Data1.
Patch 2 makes F12 read only the registers up to and including Data1,
raising the report rate to about 65 Hz on this machine. Patch 3 then
adds LEN2072 to smbus_pnp_ids and should not be applied without
patch 2.

Tested on a ThinkPad P14s Gen 2i (20VX) on 7.2.9, including s2idle
suspend/resume and the TrackPoint on the RMI4 pass-through port. On
this device Data1 is the first data register, so patch 1 does not
change its behavior.

Changes in v2:
- New patch 1. Sashiko pointed out that with patch 2 alone, on devices
  where Data1 is not at offset 0, rmi_f12_process_objects() could parse
  bytes past the end of what was read. The underlying off-by-
  data1_offset bound predates this series, so it is fixed separately
  with a Fixes: tag.
- No changes to patches 2 and 3.

v1: https://lore.kernel.org/all/20261026093118.2312302-1-dmitry@kernelgen.org/

Dmitry Mikushin (3):
  Input: synaptics-rmi4 - f12: pass Data1-relative size to
    process_objects
  Input: synaptics-rmi4 - f12: read only the object data on attention
  Input: synaptics - add LEN2072 to smbus_pnp_ids for ThinkPad P14s Gen
    2i

 drivers/input/mouse/synaptics.c |  1 +
 drivers/input/rmi4/rmi_f12.c    | 20 +++++++++++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

-- 
2.56.0