On 10/27/25 15:59, Neil Armstrong wrote:
Hi,
On 9/18/25 16:02, Jens Reidel wrote:
These ICs support SPI and I2C interfaces, up to 10 finger touch, stylus
and gesture events.
This driver is derived from the Goodix gtx8_driver_linux available at
[1] and only supports the GT9886 and GT9896 ICs present in the Xiaomi
Mi 9T and Xiaomi Redmi Note 10 Pro smartphones.
The current implementation only supports Normandy and Yellowstone type
ICs, aka only GT9886 and GT9896. It is also limited to I2C only, since I
don't have a device with GTX8 over SPI at hand. Adding support for SPI
should be fairly easy in the future, since the code uses a regmap.
You didn't explain why you didn't integrate with goodix_berlin or at least
try to reuse part of the code.
Neil
Hi Neil,
I've taken a lot of inspiration from the goodix_berlin driver, but the
Berlin and GTX8 series of touchscreen ICs differ quite a bit. The driver
architecture is the same overall, i.e. the power-up sequence and general
concepts are the mostly same, but it is very clear that they are
different generations when looking at it in more detail.
Some of the differences:
- There is no equivalent to the bootoption reg that I can find in the
public GTX8 drivers
- Firmware version struct layout is different yet again
- GTX8 does not expose IC information at runtime as far as I can tell
- The checksum method differs yet again
- The vendor driver reads only 1 touch upfront rather than 2
- Register addresses are 16-bit on GTX8 and 32-bit on Berlin
- Firmware requests don't appear to really exist on GTX8
From what I can tell, the evolution seems to be:
Normandy -> Yellowstone -> Berlin
since Normandy and Yellowstone are already quite different (especially
with the way checksums work) and Yellowstone has a couple of things
(checksum, fw_version) that appear similar to Berlin series ICs.
I've tried to make the Berlin driver work for GTX8 ICs before, but
they're so different (and I lack documentation for registers to perhaps
make some parts work on GTX8) that I'd rather support these ICs in a new
and tiny driver. I hope that makes sense. I took heavy inspiration from
the Berlin driver, but the only parts that are really common between
them are very trivial things like e.g. the input dev config or power on,
which I don't think are worth putting in a separate header.
Best regards,
Jens
Support for advanced features like:
- Firmware updates
- Stylus events
- Gesture events
- Nanjing IC support
is not included in current version.
The current support requires a previously flashed firmware to be
present.
As I did not have access to datasheets for these ICs, I extracted the
addresses from a couple of config files using a small tool [2]. The
addresses are identical for the same IC families in all configs I
observed, however not all of them make sense and I stubbed out firmware
request support due to this.
[1] https://github.com/goodix/gtx8_driver_linux
[2] https://github.com/sm7150-mainline/goodix-cfg-bin
Signed-off-by: Jens Reidel <[email protected]>
---
Jens Reidel (3):
dt-bindings: input: document Goodix GTX8 Touchscreen ICs
Input: add support for Goodix GTX8 Touchscreen ICs
MAINTAINERS: add an entry for Goodix GTX8 Touchscreen driver
.../bindings/input/touchscreen/goodix,gt9886.yaml | 71 +++
MAINTAINERS | 7 +
drivers/input/touchscreen/Kconfig | 15 +
drivers/input/touchscreen/Makefile | 1 +
drivers/input/touchscreen/goodix_gtx8.c | 562 +++++++++++
++++++++++
drivers/input/touchscreen/goodix_gtx8.h | 137 +++++
6 files changed, 793 insertions(+)
---
base-commit: ae2d20002576d2893ecaff25db3d7ef9190ac0b6
change-id: 20250918-gtx8-59a50ccd78a5
Best regards,
