0306f03573
ACPICA commit b9dc31e2fc67cf196fab5253a9a673bee68b2ef5 Before this commit acpi_ev_execute_reg_methods() had special handling to handle "orphan" (no matching op_region declared) _REG methods for EC nodes. On Intel Cherry Trail devices there are 2 possible ACPI op_regions for accessing GPIOs. The standard general_purpose_io op_region and the Cherry Trail specific user_defined 0x9X op_regions. Having 2 different types of op_regions leads to potential issues with checks for op_region availability, or in other words checks if _REG has been called for the op_region which the ACPI code wants to use. Except for the "orphan" EC handling, ACPICA core does not call _REG on an ACPI node which does not define an op_region matching the type being registered; and the reference design DSDT, from which most Cherry Trail DSDTs are derived, does not define general_purpose_io, nor user_defined(0x93) op_regions for the GPO2 (UID 3) device, because no pins were assigned ACPI controlled functions in the reference design. Together this leads to the perfect storm, at least on the Cherry Trail based Medion Akayo E1239T. This design does use a GPO2 pin from its ACPI code and has added the Cherry Trail specific user_defined(0x93) opregion to its GPO2 ACPI node to access this pin. But it uses a has _REG been called availability check for the standard general_purpose_io op_region. This clearly is a bug in the DSDT, but this does work under Windows. This issue leads to the intel_vbtn driver reporting the device always being in tablet-mode at boot, even if it is in laptop mode. Which in turn causes userspace to ignore touchpad events. So iow this issues causes the touchpad to not work at boot. This commit fixes this by extending the "orphan" _REG method handling to also apply to GPIO address-space handlers. Note it seems that Windows always calls "orphan" _REG methods so me may want to consider dropping the space-id check and always do "orphan" _REG method handling. Link: https://github.com/acpica/acpica/commit/b9dc31e2 Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Erik Kaneda <erik.kaneda@intel.com> Signed-off-by: Bob Moore <robert.moore@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> |
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README
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.