SBBR : _AEI & _EVT methods should not be mandatory

[Samer EL-Haj-Mahmoud]

FWTS has a test for _AEI method: https://git.launchpad.net/fwts/tree/src/acpi/method/method.c#n570

And the usage of _EVT https://git.launchpad.net/fwts/tree/src/acpi/method/method.c#n659

The tests treat these methods as mandatory for SBBR, but optional otherwise.

This is incorrect per the latest SBBR definition.

The BBR 1.0 specification (which defines the latest SBBR requirements: https://developer.arm.com/documentation/den0044/latest) clarifies that _AEI is not mandatory. Sections 8.5.3 and 8.5.4 describe the two methods for reporting ACPI events (with GPIO or Generic Event Device/interrupts). And section 8.2 clarifies that the requirement is that either method is present:

"
8.2 ACPI provided data structures
Provide either Interrupt-signaled Events (see ACPI § 5.6.9) or GPIO-signaled Events (see ACPI § 5.6.5 )
for the conveyance of runtime event notifications, from the system firmware to the Operating System
Power Management (OSPM).
"

This clarifies that BBR requires that either GPIO-signaled events (using _AEI and _EVT), OR Generic Event Device with interrupt signaled events (using _CRS and _EVT) are provided. Also, both of these methods are required only if the HW has such capability (which is a separate requirement on the HW itself, see BBR 1.0 section 8.6)

[Alex Hung (alexhung)]

Patch under review: https://patchwork<email address hidden>/

[Alex Hung (alexhung)]

A fixed is applied and will be included in July release.