[PATCH] ACPI / OSI: Add OEM _OSI string to enable dGPU direct output

[Alex Hung]

For HP Inc. mobile workstation with hybrid graphics support, dGPU can
directly output to external monitors; however, Nvidia and AMD's Linux
drivers aren't able to support this feature.

The OEM _OSI string "Linux-HPI-Hybrid-Graphics" is used by BIOS to
implement dGPU direct output to external monitors.

The form of the OEM _OSI strings is defined by each OEMs and is
discussed in Documentation/acpi/osi.txt.

BugLink: http://bugs.launchpad.net/bugs/1810702

Signed-off-by: Alex Hung <alex.hung at canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
(cherry picked from commit 28586a51eea666d5531bcaef2f68e4abbd87242c)
Signed-off-by: Alex Hung <alex.hung at canonical.com>
---
 drivers/acpi/osi.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
index e83297e..09053a2 100644
--- a/drivers/acpi/osi.c
+++ b/drivers/acpi/osi.c
@@ -74,6 +74,13 @@ osi_setup_entries[OSI_STRING_ENTRIES_MAX] __initdata = {
 	 * a BIOS workaround.
 	 */
 	{"Linux-Lenovo-NV-HDMI-Audio", true},
+	/*
+	 * Linux-HPI-Hybrid-Graphics is used by BIOS to enable dGPU to
+	 * output video directly to external monitors on HP Inc. mobile
+	 * workstations as Nvidia and AMD VGA drivers provide limited
+	 * hybrid graphics supports.
+	 */
+	{"Linux-HPI-Hybrid-Graphics", true},
 };
 
 static u32 acpi_osi_handler(acpi_string interface, u32 supported)
-- 
2.7.4