007e50eb5d
The HiDeep IST940E touchscreen controller used on the Lenovo Yoga Book X90F convertible comes up in HID mode by default. This works well on the X91F Windows model where the touchscreen is correctly described in ACPI and ACPI takes care of controlling the reset GPIO and regulators. But the X90F ships with Android and the ACPI tables on this model don't describe the touchscreen. Instead this is hardcoded in the vendor kernel. The vendor kernel uses the touchscreen in native HiDeep 20 (2.0?) protocol mode and switches the controller to this mode by writing 0 to reg 0x081e. Adjusting the i2c-hid code to deal with the reset-gpio and regulators on this non devicetree (but rather broken ACPI) convertible is somewhat tricky and the native protocol reports ABS_MT_PRESSURE and ABS_MT_TOUCH_MAJOR which are not reported in HID mode, so it is preferable to use the native mode. Add support to the hideep driver to reset the work-mode to the native HiDeep protocol to allow using it on the Lenovo Yoga Book X90F. This is guarded behind a new "hideep,force-native-protocol" boolean property, to avoid changing behavior on other devices. For the record: I did test using the i2c-hid driver with some quick hacks and it does work. The I2C-HID descriptor is available from address 0x0020, just like on the X91F Windows model. So far the new "hideep,force-native-protocol" property is only used on x86/ACPI (non devicetree) devs. IOW it is not used in actual devicetree files. The devicetree-bindings maintainers have requested properties like these to not be added to the devicetree-bindings, so the new property is deliberately not added to the existing devicetree-bindings. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20230311114726.182789-3-hdegoede@redhat.com Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.