On Tue, 26 Apr 2022, Jouni Högander jouni.hogander@intel.com wrote:
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.
IMO all of this should be computed at EDID parsing time once and stored in the metadata. Maybe in drm_parse_hdr_metadata_block().
Over time we've added a bunch of functions to do this type of stuff, and all drivers call them at slightly different times and different ways, and it just grows complicated.
(Also, I think basically everything that comes out of the EDID or DisplayID should be stored in connector->display_info instead of being spread around like we currently do. But that's for another patch series, another time.)
BR, Jani.
Cc: Rodrigo Siqueira Rodrigo.Siqueira@amd.com Cc: Harry Wentland harry.wentland@amd.com Cc: Lyude Paul lyude@redhat.com Cc: Mika Kahola mika.kahola@intel.com Cc: Jani Nikula jani.nikula@intel.com Signed-off-by: Jouni Högander jouni.hogander@intel.com
drivers/gpu/drm/drm_edid.c | 55 ++++++++++++++++++++++++++++++++++++++ include/drm/drm_edid.h | 4 +++ 2 files changed, 59 insertions(+)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 7a8482b75071..1cb886debbbe 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -4005,6 +4005,61 @@ drm_display_mode_from_cea_vic(struct drm_device *dev, } EXPORT_SYMBOL(drm_display_mode_from_cea_vic);
+/**
- drm_luminance_range_from_static_hdr_metadata() - luminance range from static hdr
- metadata
- @connector: connector we're calculating for
- @min: Calculated min value
- @max: Calculated max value
- Calculates backlight min and max as described in CTA-861-G
- Returns: True when calculation succeeds.
- */
+bool +drm_luminance_range_from_static_hdr_metadata(struct drm_connector *connector,
u32 *min, u32 *max)+{
- struct hdr_sink_metadata *hdr_metadata = &connector->hdr_sink_metadata;
- 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 min_cll, max_cll, q, r;
- if (!(hdr_metadata->hdmi_type1.metadata_type &
BIT(HDMI_STATIC_METADATA_TYPE1)))return false;- max_cll = hdr_metadata->hdmi_type1.max_cll;
- min_cll = hdr_metadata->hdmi_type1.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_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);
- return true;
+} +EXPORT_SYMBOL(drm_luminance_range_from_static_hdr_metadata);
static int do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len) { diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h index c3204a58fb09..63e441c84d72 100644 --- a/include/drm/drm_edid.h +++ b/include/drm/drm_edid.h @@ -406,6 +406,10 @@ drm_hdmi_avi_infoframe_quant_range(struct hdmi_avi_infoframe *frame, const struct drm_display_mode *mode, enum hdmi_quantization_range rgb_quant_range);
+bool +drm_luminance_range_from_static_hdr_metadata(struct drm_connector *connector,
u32 *min, u32 *max);/**
- drm_eld_mnl - Get ELD monitor name length in bytes.
- @eld: pointer to an eld memory structure with mnl set