From 364438fd629f7611a84c8e6d7de91659300f1502 Mon Sep 17 00:00:00 2001
From: Nicholas Bishop <nicholasbishop@google.com>
Date: Fri, 11 Feb 2022 14:57:39 -0500
Subject: [PATCH] drm/radeon: Fix backlight control on iMac 12,1
Git-commit: 364438fd629f7611a84c8e6d7de91659300f1502
Patch-mainline: v5.17-rc5
References: git-fixes
The iMac 12,1 does not use the gmux driver for backlight, so the radeon
backlight device is needed to set the brightness.
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1838
Signed-off-by: Nicholas Bishop <nicholasbishop@google.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/radeon/atombios_encoders.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
index 0fce73b9a646..70bd84b7ef2b 100644
--- a/drivers/gpu/drm/radeon/atombios_encoders.c
+++ b/drivers/gpu/drm/radeon/atombios_encoders.c
@@ -198,7 +198,8 @@ void radeon_atom_backlight_init(struct radeon_encoder *radeon_encoder,
* so don't register a backlight device
*/
if ((rdev->pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE) &&
- (rdev->pdev->device == 0x6741))
+ (rdev->pdev->device == 0x6741) &&
+ !dmi_match(DMI_PRODUCT_NAME, "iMac12,1"))
return;
if (!radeon_encoder->enc_priv)
--
2.31.1