Commit 2ca8e628 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

Revert "ACPI: Pass the same capabilities to the _OSC regardless of the query flag" 

Revert commit 159d8c27 ("ACPI: Pass the same capabilities to the
_OSC regardless of the query flag") which caused legitimate usage
scenarios (when the platform firmware does not want the OS to control
certain platform features controlled by the system bus scope _OSC) to
break and was misguided by some misleading language in the _OSC
definition in the ACPI specification (in particular, Section 6.2.11.1.3
"Sequence of _OSC Calls" that contradicts other perts of the _OSC
definition).

Link: https://lore.kernel.org/linux-acpi/CAJZ5v0iStA0JmO0H3z+VgQsVuQONVjKPpw0F5HKfiq=Gb6B5yw@mail.gmail.com


Reported-by: default avatarMario Limonciello <Mario.Limonciello@amd.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Acked-by: default avatarHuang Rui <ray.huang@amd.com>
Reviewed-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
parent 3c36fe93

drivers/acpi/bus.c

+19 −8
Original line number Diff line number Diff line
@@ -332,21 +332,32 @@ static void acpi_bus_osc_negotiate_platform_control(void) 
	if (ACPI_FAILURE(acpi_run_osc(handle, &context)))

		return;



	capbuf_ret = context.ret.pointer;

	if (context.ret.length <= OSC_SUPPORT_DWORD) {

		kfree(context.ret.pointer);

		return;

	}



	/* Now run _OSC again with query flag clear */

	/*

	 * Now run _OSC again with query flag clear and with the caps

	 * supported by both the OS and the platform.

	 */

	capbuf[OSC_QUERY_DWORD] = 0;

	capbuf[OSC_SUPPORT_DWORD] = capbuf_ret[OSC_SUPPORT_DWORD];

	kfree(context.ret.pointer);



	if (ACPI_FAILURE(acpi_run_osc(handle, &context)))

		return;



	capbuf_ret = context.ret.pointer;

	if (context.ret.length > OSC_SUPPORT_DWORD) {

		osc_sb_apei_support_acked =

			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_APEI_SUPPORT;

		osc_pc_lpi_support_confirmed =

			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_PCLPI_SUPPORT;

		osc_sb_native_usb4_support_confirmed =

			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_NATIVE_USB4_SUPPORT;

	}



	kfree(context.ret.pointer);

}