Split luminance min/max calculation using static hdr metadata from
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c:update_connector_ext_caps
into drm/drm_edid.c and use it during edid parsing. Calculated range is
stored into connector->display_info->luminance_range.
v2: Calculate range during edid parsing
Cc: Roman Li <roman.li@xxxxxxx>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
Cc: Harry Wentland <harry.wentland@xxxxxxx>
Cc: Lyude Paul <lyude@xxxxxxxxxx>
Cc: Mika Kahola <mika.kahola@xxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
Signed-off-by: Jouni Högander <jouni.hogander@xxxxxxxxx>
---
drivers/gpu/drm/drm_edid.c | 50 +++++++++++++++++++++++++++++++++++++-
1 file changed, 49 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 2bdaf1e34a9d..3b367100290f 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -5014,6 +5014,49 @@ static void fixup_detailed_cea_mode_clock(struct drm_display_mode *mode)
mode->clock = clock;
}
+static void drm_calculate_luminance_range(struct drm_connector *connector)
+{
+ struct hdr_static_metadata *hdr_metadata = &connector->hdr_sink_metadata.hdmi_type1;
+ struct drm_luminance_range_info *luminance_range =
+ &connector->display_info.luminance_range;
+ 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};
+ u32 max_avg, min_cll, max, min, q, r;
+
+ if (!(hdr_metadata->metadata_type & BIT(HDMI_STATIC_METADATA_TYPE1)))
+ return;
+
+ max_avg = hdr_metadata->max_fall;
+ min_cll = hdr_metadata->min_cll;
+
+ /* 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_avg >> 5;
+ r = max_avg % 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);
+
+ luminance_range->min_luminance = min;
+ luminance_range->max_luminance = max;
+}
+
static uint8_t eotf_supported(const u8 *edid_ext)
{
return edid_ext[2] &
@@ -5045,8 +5088,12 @@ drm_parse_hdr_metadata_block(struct drm_connector *connector, const u8 *db)
connector->hdr_sink_metadata.hdmi_type1.max_cll = db[4];
if (len >= 5)
connector->hdr_sink_metadata.hdmi_type1.max_fall = db[5];
- if (len >= 6)
+ if (len >= 6) {
connector->hdr_sink_metadata.hdmi_type1.min_cll = db[6];
+
+ /* Calculate only when all values are available */
+ drm_calculate_luminance_range(connector);
+ }
}
static void
@@ -5951,6 +5998,7 @@ drm_reset_display_info(struct drm_connector *connector)
info->non_desktop = 0;
memset(&info->monitor_range, 0, sizeof(info->monitor_range));
+ memset(&info->luminance_range, 0, sizeof(info->luminance_range));
info->mso_stream_count = 0;
info->mso_pixel_overlap = 0;
--
2.25.1
