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Various 360 degree hinges (yoga) style 2-in-1 devices use 2 accelerometers to allow the OS to determine the angle between the display and the base of the device. On Windows these are read by a special HingeAngleService process which calls undocumented ACPI methods, to let the firmware know if the 2-in-1 is in tablet- or laptop-mode. The firmware may use this to disable the kbd and touchpad to avoid spurious input in tablet-mode as well as to report SW_TABLET_MODE info to the OS. Since Linux does not call these undocumented methods, the SW_TABLET_MODE info reported by various pdx86 drivers is incorrect on these devices. Before this commit the intel-hid and thinkpad_acpi code already had 2 hardcoded checks for ACPI hardware-ids of dual-accel sensors to avoid reporting broken info. And now we also have a bug-report about the same problem in the intel-vbtn code. Since there are at least 3 different ACPI hardware-ids in play, add a new dual_accel_detect() helper which checks for all 3, rather then adding different hardware-ids to the drivers as bug-reports trickle in. Having shared code which checks all known hardware-ids is esp. important for the intel-hid and intel-vbtn drivers as these are generic drivers which are used on a lot of devices. The BOSC0200 hardware-id requires special handling, because often it is used for a single-accelerometer setup. Only in a few cases it refers to a dual-accel setup, in which case there will be 2 I2cSerialBus resources in the device's resource-list, so the helper checks for this. BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209011 Reported-and-tested-by: Julius Lehmann <julius@devpi.de> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Link: https://lore.kernel.org/r/20210729082134.6683-1-hdegoede@redhat.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.