[PATCH 5.10 69/84] drm/amd/display: Cap OLED brightness per max frame-average luminance

Greg Kroah-Hartman
2022-06-20T13:14:57Z

From: Roman Li <roman.li@amd.com>

commit 4fd17f2ac0aa4e48823ac2ede5b050fb70300bf4 upstream.

[Why]
For OLED eDP the Display Manager uses max_cll value as a limit
for brightness control.
max_cll defines the content light luminance for individual pixel.
Whereas max_fall defines frame-average level luminance.
The user may not observe the difference in brightness in between
max_fall and max_cll.
That negatively impacts the user experience.

[How]
Use max_fall value instead of max_cll as a limit for brightness control.

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.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/amd/display/amdgpu_dm/amdgpu_dm.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2141,7 +2141,7 @@ static struct drm_mode_config_helper_fun

static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
{
- u32 max_cll, min_cll, max, min, q, r;
+ u32 max_avg, min_cll, max, min, q, r;
struct amdgpu_dm_backlight_caps *caps;
struct amdgpu_display_manager *dm;
struct drm_connector *conn_base;
@@ -2164,7 +2164,7 @@ static void update_connector_ext_caps(st
caps = &dm->backlight_caps;
caps->ext_caps = &aconnector->dc_link->dpcd_sink_ext_caps;
caps->aux_support = false;
- max_cll = conn_base->hdr_sink_metadata.hdmi_type1.max_cll;
+ max_avg = conn_base->hdr_sink_metadata.hdmi_type1.max_fall;
min_cll = conn_base->hdr_sink_metadata.hdmi_type1.min_cll;

if (caps->ext_caps->bits.oled == 1 /*||
@@ -2192,8 +2192,8 @@ static void update_connector_ext_caps(st
* The results of the above expressions can be verified at
* pre_computed_values.
*/
- q = max_cll >> 5;
- r = max_cll % 32;
+ q = max_avg >> 5;
+ r = max_avg % 32;
max = (1 << q) * pre_computed_values[r];

// min luminance: maxLum * (CV/255)^2 / 100