ACPI / EC: Add support to skip boot stage DSDT probe
We prepared _INI/_STA methods for \_SB, \_SB.PCI0, \_SB.LID0 and \_SB.EC, _HID(PNP0C09)/_CRS/_GPE for \_SB.EC to poke Windows behavior with qemu, we got the following execution sequence: \_SB._INI \_SB.PCI0._STA \_SB.LID0._STA \_SB.EC._STA \_SB.PCI0._INI \_SB.LID0._INI \_SB.EC._INI There is no extra DSDT EC device enumeration process occurring before the main ACPI device enumeration process. That means acpi_ec_dsdt_probe() is not Windows-compatible. Tracking back, it was added by the following commit: Commit: c5279dee Subject: ACPI: EC: Add some basic check for ECDT data but that commit was misguided. Why we shouldn't enumerate DSDT EC before the main ACPI device enumeration? The only way to know if the DSDT EC is valid would be to evaluate its _STA control method, but it's not safe to evaluate this control method that early and out of the ACPI enumeration process, because _STA may refer to entities (such as resources or ACPI device objects) that may not have been initialized before OSPM starts to enumerate them via the main ACPI device enumeration. But after we had reverted back to the expected behavior, a regression was reported. On that platform, there is no ECDT, but the platform control methods access EC operation region earlier than Linux expects causing some ACPI method execution errors. For this reason, we just go back to old behavior to still probe DSDT EC as the boot EC. However, that turns out to lead to yet another functional breakage and in order to work around all of the problems, we skip boot stage DSDT probe when the ECDT exists so that a later quirk can always use correct ECDT GPE setting. Link: http://bugzilla.kernel.org/show_bug.cgi?id=11880 Link: http://bugzilla.kernel.org/show_bug.cgi?id=119261 Link: http://bugzilla.kernel.org/show_bug.cgi?id=195651Tested-by: Daniel Drake <drake@endlessm.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> [ rjw: Changelog & comments massage ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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