From c573e240609ff781a0246c0c8c8351abd0475287 Mon Sep 17 00:00:00 2001
From: Mario Limonciello <mario.limonciello@amd.com>
Date: Thu, 8 Dec 2022 10:42:06 -0600
Subject: [PATCH] drm/amd/display: Report to ACPI video if no panels were found
Git-commit: c573e240609ff781a0246c0c8c8351abd0475287
Patch-mainline: v6.2-rc2
References: bsc#1206843

On desktop APUs amdgpu doesn't create a native backlight device
as no eDP panels are found.  However if the BIOS has reported
backlight control methods in the ACPI tables then an acpi_video0
backlight device will be made 8 seconds after boot.

This has manifested in a power slider on a number of desktop APUs
ranging from Ryzen 5000 through Ryzen 7000 on various motherboard
manufacturers. To avoid this, report to the acpi video detection
that the system does not have any panel connected in the native
driver.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1783786
Reported-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 77277d90b6e2..a7eb13902af8 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4360,6 +4360,10 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 		amdgpu_set_panel_orientation(&aconnector->base);
 	}
 
+	/* If we didn't find a panel, notify the acpi video detection */
+	if (dm->adev->flags & AMD_IS_APU && dm->num_of_edps == 0)
+		acpi_video_report_nolcd();
+
 	/* Software is initialized. Now we can register interrupt handlers. */
 	switch (adev->asic_type) {
 #if defined(CONFIG_DRM_AMD_DC_SI)
-- 
2.35.3