[PATCH 2/3] drm/amdgpu_dm: Use split out luminance calculation function

[Jouni Högander]

Luminance range was split out into drm_edid.c to share the calculation
function. Use this new interface for caps->aux_max_input_signal and
caps->aux_min_input_signal.

Cc: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
Cc: Harry Wentland <harry.wentland at amd.com>
Cc: Lyude Paul <lyude at redhat.com>
Cc: Mika Kahola <mika.kahola at intel.com>
Cc: Jani Nikula <jani.nikula at intel.com>
Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 35 +++----------------
 1 file changed, 4 insertions(+), 31 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 2ade82cfb1ac..49c03400e962 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2836,15 +2836,11 @@ static struct drm_mode_config_helper_funcs amdgpu_dm_mode_config_helperfuncs = {
 
 static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
 {
-	u32 max_cll, min_cll, max, min, q, r;
 	struct amdgpu_dm_backlight_caps *caps;
 	struct amdgpu_display_manager *dm;
 	struct drm_connector *conn_base;
 	struct amdgpu_device *adev;
 	struct dc_link *link = NULL;
-	static const u8 pre_computed_values[] = {
-		50, 51, 52, 53, 55, 56, 57, 58, 59, 61, 62, 63, 65, 66, 68, 69,
-		71, 72, 74, 75, 77, 79, 81, 82, 84, 86, 88, 90, 92, 94, 96, 98};
 	int i;
 
 	if (!aconnector || !aconnector->dc_link)
@@ -2866,8 +2862,6 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
 	caps = &dm->backlight_caps[i];
 	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;
-	min_cll = conn_base->hdr_sink_metadata.hdmi_type1.min_cll;
 
 	if (caps->ext_caps->bits.oled == 1 /*||
 	    caps->ext_caps->bits.sdr_aux_backlight_control == 1 ||
@@ -2879,31 +2873,10 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
 	else if (amdgpu_backlight == 1)
 		caps->aux_support = true;
 
-	/* From the specification (CTA-861-G), for calculating the maximum
-	 * luminance we need to use:
-	 *	Luminance = 50*2**(CV/32)
-	 * Where CV is a one-byte value.
-	 * For calculating this expression we may need float point precision;
-	 * to avoid this complexity level, we take advantage that CV is divided
-	 * by a constant. From the Euclids division algorithm, we know that CV
-	 * can be written as: CV = 32*q + r. Next, we replace CV in the
-	 * Luminance expression and get 50*(2**q)*(2**(r/32)), hence we just
-	 * need to pre-compute the value of r/32. For pre-computing the values
-	 * We just used the following Ruby line:
-	 *	(0...32).each {|cv| puts (50*2**(cv/32.0)).round}
-	 * The results of the above expressions can be verified at
-	 * pre_computed_values.
-	 */
-	q = max_cll >> 5;
-	r = max_cll % 32;
-	max = (1 << q) * pre_computed_values[r];
-
-	// min luminance: maxLum * (CV/255)^2 / 100
-	q = DIV_ROUND_CLOSEST(min_cll, 255);
-	min = max * DIV_ROUND_CLOSEST((q * q), 100);
-
-	caps->aux_max_input_signal = max;
-	caps->aux_min_input_signal = min;
+	if (!drm_luminance_range_from_static_hdr_metadata(conn_base,
+							  &caps->aux_min_input_signal,
+							  &caps->aux_max_input_signal))
+		DRM_ERROR("No backligt range in static hdr metadata\n");
 }
 
 void amdgpu_dm_update_connector_after_detect(
-- 
2.25.1