[PATCH AUTOSEL 5.13 09/11] drm/amdgpu/display: only enable aux backlight control for OLED panels

[Sasha Levin]

From: Alex Deucher <alexander.deucher at amd.com>

[ Upstream commit f2ad3accefc63e72e9932e141c21875cc04beec8 ]

We've gotten a number of reports about backlight control not
working on panels which indicate that they use aux backlight
control.  A recent patch:

commit 2d73eabe2984a435737498ab39bb1500a9ffe9a9
Author: Camille Cho <Camille.Cho at amd.com>
Date:   Thu Jul 8 18:28:37 2021 +0800

    drm/amd/display: Only set default brightness for OLED

    [Why]
    We used to unconditionally set backlight path as AUX for panels capable
    of backlight adjustment via DPCD in set default brightness.

    [How]
    This should be limited to OLED panel only since we control backlight via
    PWM path for SDR mode in LCD HDR panel.

    Reviewed-by: Krunoslav Kovac <krunoslav.kovac at amd.com>
    Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
    Signed-off-by: Camille Cho <Camille.Cho at amd.com>
    Signed-off-by: Alex Deucher <alexander.deucher at amd.com>

Changes some other code to only use aux for backlight control on
OLED panels.  The commit message seems to indicate that PWM should
be used for SDR mode on HDR panels.  Do something similar for
backlight control in general.  This may need to be revisited if and
when HDR started to get used.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1438
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=213715
Reviewed-by: Roman Li <Roman.Li at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

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 eeaae1cf2bc2..f02ad2eb154b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2367,9 +2367,9 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
 	max_cll = conn_base->hdr_sink_metadata.hdmi_type1.max_cll;
 	min_cll = conn_base->hdr_sink_metadata.hdmi_type1.min_cll;
 
-	if (caps->ext_caps->bits.oled == 1 ||
+	if (caps->ext_caps->bits.oled == 1 /*||
 	    caps->ext_caps->bits.sdr_aux_backlight_control == 1 ||
-	    caps->ext_caps->bits.hdr_aux_backlight_control == 1)
+	    caps->ext_caps->bits.hdr_aux_backlight_control == 1*/)
 		caps->aux_support = true;
 
 	if (amdgpu_backlight == 0)
-- 
2.30.2