With the growing popularity of running upstream Linux on mobile devices,
we're beginning to run into more and more edgecases. The OnePlus 6 is a
fairly well supported 2018 era smartphone, selling over a million units
in it's first 22 days. With this level of popularity, it's almost
inevitable that we get third party replacement displays, and as a
result, replacement touchscreen controllers.
The OnePlus 6 shipped with an extremely usecase specific touchscreen
driver, it implemented only the bare minimum parts of the highly generic
rmi4 protocol, instead hardcoding most of the register addresses.
As a result, the third party touchscreen controllers that are often
found in replacement screens, implement only the registers that the
downstream driver reads from. They additionally have other restrictions
such as heavy penalties on unaligned reads.
This series attempts to implement the necessary workaround to support
some of these chips with the rmi4 driver. Although it's worth noting
that at the time of writing there are other unofficial controllers in
the wild that don't work even with these patches.
We have been shipping these patches in postmarketOS for the last several
years, and they are known to not cause any regressions on the OnePlus
6/6T (with the official Synaptics controller), however I don't own any
other rmi4 hardware to further validate this.
The series is also available (until merged) at
https://gitlab.com/sdm845/sdm845-next/-/commits/b4/synaptics-rmi4
---
Changes in v6:
- Rebased on top of next-20251113.
- No other change since the Rob Herring comment.
- Link to v5: https://lore.kernel.org/r/20250410-synaptics-rmi4-v5-0-b41bb90f78b9@ixit.cz
Changes in v5:
- Removed -i2c suffix from rmi4-s3706b-i2c (Krzysztof).
- Link to v4: https://lore.kernel.org/r/20250402-synaptics-rmi4-v4-0-1bb95959e564@ixit.cz
Changes in v4:
- Replaced patch "dt-bindings: input: syna,rmi4: document syna,pdt-fallback-desc"
with patch documenting specific touchscreen model used in OnePlus 6 and 6T.
- Fixed zero electrode return code (Dmitry).
- Switched the duplicate detection algo to bitmap (Dmitry).
- Optimized rmi_device_platform_data struct to avoid unnecessary
padding.
- Changed fallback_size from int to unsigned int.
- Changed SoB from nickname and old address (methanal <baclofen@tuta.io>) to
Kaustabh Chakraborty <kauschluss@disroot.org>.
Verified ownership through the sdm845 chatroom on Matrix.
- Link to v3: https://lore.kernel.org/r/20250308-synaptics-rmi4-v3-0-215d3e7289a2@ixit.cz
Changes in v3:
- reworded dt-bindings property description
- fixed the rmi_driver_of_probe definition for non device-tree builds.
- fixed some indentation issues reported by checkpatch
- change rmi_pdt_entry_is_valid() variable to unsigned
- Link to v2: https://lore.kernel.org/all/20230929-caleb-rmi4-quirks-v2-0-b227ac498d88@linaro.org
Changes in v2:
- Improve dt-bindings patch (thanks Rob)
- Add missing cast in patch 5 to fix the pointer arithmetic
- Link to v1: https://lore.kernel.org/r/20230929-caleb-rmi4-quirks-v1-0-cc3c703f022d@linaro.org
---
Casey Connolly (1):
Input: synaptics-rmi4 - handle duplicate/unknown PDT entries
David Heidelberg (1):
dt-bindings: input: syna,rmi4: Document syna,rmi4-s3706b
Kaustabh Chakraborty (5):
Input: synaptics-rmi4 - f12: use hardcoded values for aftermarket touch ICs
Input: synaptics-rmi4 - f55: handle zero electrode count
Input: synaptics-rmi4 - don't do unaligned reads in IRQ context
Input: synaptics-rmi4 - read product ID on aftermarket touch ICs
Input: synaptics-rmi4 - support fallback values for PDT descriptor bytes
.../devicetree/bindings/input/syna,rmi4.yaml | 11 +-
drivers/input/rmi4/rmi_driver.c | 124 +++++++++++++++++----
drivers/input/rmi4/rmi_driver.h | 10 ++
drivers/input/rmi4/rmi_f01.c | 14 +++
drivers/input/rmi4/rmi_f12.c | 117 ++++++++++++++-----
drivers/input/rmi4/rmi_f55.c | 5 +
include/linux/rmi.h | 3 +
7 files changed, 234 insertions(+), 50 deletions(-)
---
base-commit: 6d7e7251d03f98f26f2ee0dfd21bb0a0480a2178
change-id: 20250308-synaptics-rmi4-c832b2f73ceb
Best regards,
--
David Heidelberg <david@ixit.cz>