[PATCH 1/2] drm/amd/display: Fix the brightness read via aux

[Takashi Iwai]

The current code tries to read the brightness value via
dc_link_get_backlight_level() no matter whether it's controlled via
aux or not, and this results in a bogus value returned.
Fix it to read the current value via
dc_link_get_backlight_level_nits() for the aux.

BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1180749
BugLink: https://gitlab.freedesktop.org/drm/amd/-/issues/1438
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c   | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

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 c6da89df055d..fb62886ae013 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -3140,6 +3140,16 @@ static int set_backlight_via_aux(struct dc_link *link, uint32_t brightness)
 	return rc ? 0 : 1;
 }
 
+static int get_backlight_via_aux(struct dc_link *link)
+{
+	uint32_t avg, peak;
+
+	if (!link ||
+	    !dc_link_get_backlight_level_nits(link, &avg, &peak))
+		return DC_ERROR_UNEXPECTED;
+	return avg;
+}
+
 static int get_brightness_range(const struct amdgpu_dm_backlight_caps *caps,
 				unsigned *min, unsigned *max)
 {
@@ -3212,8 +3222,13 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
 static int amdgpu_dm_backlight_get_brightness(struct backlight_device *bd)
 {
 	struct amdgpu_display_manager *dm = bl_get_data(bd);
-	int ret = dc_link_get_backlight_level(dm->backlight_link);
+	struct dc_link *link = (struct dc_link *)dm->backlight_link;
+	int ret;
 
+	if (dm->backlight_caps.aux_support)
+		ret = get_backlight_via_aux(link);
+	else
+		ret = dc_link_get_backlight_level(link);
 	if (ret == DC_ERROR_UNEXPECTED)
 		return bd->props.brightness;
 	return convert_brightness_to_user(&dm->backlight_caps, ret);
-- 
2.26.2