diff options
Diffstat (limited to 'drivers/gpu/drm/drm_edid.c')
| -rw-r--r-- | drivers/gpu/drm/drm_edid.c | 52 |
1 files changed, 51 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index eaa819381281..4005dab6147d 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -5165,6 +5165,51 @@ 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] & @@ -5196,8 +5241,12 @@ 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 @@ -6113,6 +6162,7 @@ static void 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; |