Revert "drm/amd/display: set backlight level limit to 1"

This reverts commit 0cafc82fae41531b0162150f9a97f2c74f97118f.

This breaks some apps that assume 0 is minimum brightness.

Revert for 4.20.  This is fixed properly for drm-next/4.21 in:
"drm/amd: Don't fail on backlight = 0"
However, that patch depends on more extensive changes to the
backlight interface which are too invasive for -fixes.

Fixes: Bugzilla: https://bugs.freedesktop.org/108668
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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 b0df6dc..e224f23 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1524,13 +1524,6 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
 {
        struct amdgpu_display_manager *dm = bl_get_data(bd);
 
-       /*
-        * PWM interperts 0 as 100% rather than 0% because of HW
-        * limitation for level 0.So limiting minimum brightness level
-        * to 1.
-        */
-       if (bd->props.brightness < 1)
-               return 1;
        if (dc_link_set_backlight_level(dm->backlight_link,
                        bd->props.brightness, 0, 0))
                return 0;