From 1a5f62a3c6942b280835cb7a35319f14ae947396 Mon Sep 17 00:00:00 2001
From: Alex Hung <alex.hung@canonical.com>
Date: Sun, 13 Sep 2020 16:34:03 -0600
Subject: [PATCH] ACPI: video: use ACPI backlight for HP 635 Notebook

commit b226faab4e7890bbbccdf794e8b94276414f9058 upstream.

The default backlight interface is AMD's radeon_bl0 which does not
work on this system, so use the ACPI backlight interface on it
instead.

BugLink: https://bugs.launchpad.net/bugs/1894667
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Alex Hung <alex.hung@canonical.com>
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/acpi/video_detect.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 5bcb4c01ec5f..55af78b55c51 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -282,6 +282,15 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
 		DMI_MATCH(DMI_PRODUCT_NAME, "530U4E/540U4E"),
 		},
 	},
+	/* https://bugs.launchpad.net/bugs/1894667 */
+	{
+	 .callback = video_detect_force_video,
+	 .ident = "HP 635 Notebook",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
+		DMI_MATCH(DMI_PRODUCT_NAME, "HP 635 Notebook PC"),
+		},
+	},
 
 	/* Non win8 machines which need native backlight nevertheless */
 	{