[PATCH 5.10 048/121] drm/radeon: Fix backlight control on iMac 12,1

Greg Kroah-Hartman
2022-02-21T09:25:18Z

From: Nicholas Bishop <nicholasbishop@google.com>

commit 364438fd629f7611a84c8e6d7de91659300f1502 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/radeon/atombios_encoders.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/radeon/atombios_encoders.c
+++ b/drivers/gpu/drm/radeon/atombios_encoders.c
@@ -197,7 +197,8 @@ void radeon_atom_backlight_init(struct r
* 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)