[PATCH v3 0/3] HDR aux backlight range calculation

[PATCH v3 0/3] HDR aux backlight range calculation

[Jouni Högander]

This patch set splits out static hdr metadata backlight range parsing
from gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c into gpu/drm/drm-edid.c
as a new function. This new function is then used during edid parsing
when HDR static metadata block parsing.

Calculated values are stored in a new struct drm_luminance_range
introduced into display_info. Amdgpu_dm.c and intel_dp_aux_backlight.c
are using this new data.

v3: Some clean-ups suggested by Jani Nikula
v2: Calculate the range during edid parsing and store into display_info

Cc: Roman Li <roman.li@amd.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
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>
Cc: Manasi Navare <manasi.d.navare@intel.com>

Jouni Högander (3):
  drm: New function to get luminance range based on static hdr metadata
  drm/amdgpu_dm: Rely on split out luminance calculation function
  drm/i915: Use luminance range calculated during edid parsing

 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 35 ++-----------
 drivers/gpu/drm/drm_edid.c                    | 52 ++++++++++++++++++-
 .../drm/i915/display/intel_dp_aux_backlight.c | 15 +++++-
 include/drm/drm_connector.h                   | 21 ++++++++
 4 files changed, 89 insertions(+), 34 deletions(-)

-- 
2.25.1

[PATCH v3 1/3] drm: New function to get luminance range based on static hdr metadata

[Jouni Högander]

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.

Add new data structure (drm_luminance_range_inf) to store luminance range
calculated using data from EDID's static hdr metadata block. Add this new
struct as a part of drm_display_info struct.

v3: Squashed adding drm_luminance_range_info patch here
v2: Calculate range during edid parsing

Cc: Roman Li <roman.li@amd.com>
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>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/drm_edid.c  | 52 ++++++++++++++++++++++++++++++++++++-
 include/drm/drm_connector.h | 21 +++++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index bbc25e3b7220..90a5e26eafa8 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
@@ -6101,6 +6150,7 @@ 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;
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 2c6fa746efac..248206bbd975 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -323,6 +323,22 @@ struct drm_monitor_range_info {
 	u8 max_vfreq;
 };
 
+/**
+ * struct drm_luminance_range_info - Panel's luminance range for
+ * &drm_display_info. Calculated using data in EDID
+ *
+ * This struct is used to store a luminance range supported by panel
+ * as calculated using data from EDID's static hdr metadata.
+ *
+ * @min_luminance: This is the min supported luminance value
+ *
+ * @max_luminance: This is the max supported luminance value
+ */
+struct drm_luminance_range_info {
+	u32 min_luminance;
+	u32 max_luminance;
+};
+
 /**
  * enum drm_privacy_screen_status - privacy screen status
  *
@@ -624,6 +640,11 @@ struct drm_display_info {
 	 */
 	struct drm_monitor_range_info monitor_range;
 
+	/**
+	 * @luminance_range: Luminance range supported by panel
+	 */
+	struct drm_luminance_range_info luminance_range;
+
 	/**
 	 * @mso_stream_count: eDP Multi-SST Operation (MSO) stream count from
 	 * the DisplayID VESA vendor block. 0 for conventional Single-Stream
-- 
2.25.1

[PATCH v3 2/3] drm/amdgpu_dm: Rely on split out luminance calculation function

[Jouni Högander]

Luminance range calculation was split out into drm_edid.c and is now
part of edid parsing. Rely on values calculated during edid parsing and
use these for caps->aux_max_input_signal and caps->aux_min_input_signal.

v2: Use values calculated during edid parsing

Cc: Roman Li <roman.li@amd.com>
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>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Jouni Högander <jouni.hogander@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 3e83fed540e8..eb7abdeb8653 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2903,15 +2903,12 @@ 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_avg, 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};
+	struct drm_luminance_range_info *luminance_range;
 	int i;
 
 	if (!aconnector || !aconnector->dc_link)
@@ -2933,8 +2930,6 @@ 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_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 /*||
 	    caps->ext_caps->bits.sdr_aux_backlight_control == 1 ||
@@ -2946,31 +2941,9 @@ 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_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);
-
-	caps->aux_max_input_signal = max;
-	caps->aux_min_input_signal = min;
+	luminance_range = &conn_base->display_info.luminance_range;
+	caps->aux_min_input_signal = luminance_range->min_luminance;
+	caps->aux_max_input_signal = luminance_range->max_luminance;
 }
 
 void amdgpu_dm_update_connector_after_detect(
-- 
2.25.1

[PATCH v3 3/3] drm/i915: Use luminance range calculated during edid parsing

[Jouni Högander]

Instead of using fixed 0 - 512 range use luminance range calculated
as a part of edid parsing. As a backup fall back to static 0 - 512.

v3: Clean-ups suggested by Jani Nikula
v2: Use values calculated during edid parsing

Cc: Lyude Paul <lyude@redhat.com>
Cc: Mika Kahola <mika.kahola@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
---
 .../gpu/drm/i915/display/intel_dp_aux_backlight.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index c92d5bb2326a..83af95bce98d 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -278,6 +278,8 @@ intel_dp_aux_hdr_setup_backlight(struct intel_connector *connector, enum pipe pi
 {
 	struct drm_i915_private *i915 = to_i915(connector->base.dev);
 	struct intel_panel *panel = &connector->panel;
+	struct drm_luminance_range_info *luminance_range =
+		&connector->base.display_info.luminance_range;
 	int ret;
 
 	if (panel->backlight.edp.intel.sdr_uses_aux) {
@@ -293,8 +295,17 @@ intel_dp_aux_hdr_setup_backlight(struct intel_connector *connector, enum pipe pi
 		}
 	}
 
-	panel->backlight.max = 512;
-	panel->backlight.min = 0;
+	if (luminance_range->max_luminance) {
+		panel->backlight.max = luminance_range->max_luminance;
+		panel->backlight.min = luminance_range->min_luminance;
+	} else {
+		panel->backlight.max = 512;
+		panel->backlight.min = 0;
+	}
+
+	drm_dbg_kms(&i915->drm, "Using backlight range %d..%d\n", panel->backlight.min,
+		    panel->backlight.max);
+
 	panel->backlight.level = intel_dp_aux_hdr_get_backlight(connector, pipe);
 	panel->backlight.enabled = panel->backlight.level != 0;
 
-- 
2.25.1

Re: [PATCH v3 2/3] drm/amdgpu_dm: Rely on split out luminance calculation function

[Jani Nikula]

On Tue, 19 Jul 2022, Jouni Högander <jouni.hogander@intel.com> wrote:
> Luminance range calculation was split out into drm_edid.c and is now
> part of edid parsing. Rely on values calculated during edid parsing and
> use these for caps->aux_max_input_signal and caps->aux_min_input_signal.

Harry, I'll merge patches 1 & 3 in this series through drm-misc-next,
because I think they're good to go, and fix stuff in i915.

Can I get your rb/ack to merge this patch as well, or do you want to
take this later via your tree?

BR,
Jani.


>
> v2: Use values calculated during edid parsing
>
> Cc: Roman Li <roman.li@amd.com>
> 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>
> Cc: Manasi Navare <manasi.d.navare@intel.com>
> Signed-off-by: Jouni Högander <jouni.hogander@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 3e83fed540e8..eb7abdeb8653 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -2903,15 +2903,12 @@ 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_avg, 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};
> +	struct drm_luminance_range_info *luminance_range;
>  	int i;
>  
>  	if (!aconnector || !aconnector->dc_link)
> @@ -2933,8 +2930,6 @@ 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_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 /*||
>  	    caps->ext_caps->bits.sdr_aux_backlight_control == 1 ||
> @@ -2946,31 +2941,9 @@ 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_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);
> -
> -	caps->aux_max_input_signal = max;
> -	caps->aux_min_input_signal = min;
> +	luminance_range = &conn_base->display_info.luminance_range;
> +	caps->aux_min_input_signal = luminance_range->min_luminance;
> +	caps->aux_max_input_signal = luminance_range->max_luminance;
>  }
>  
>  void amdgpu_dm_update_connector_after_detect(

-- 
Jani Nikula, Intel Open Source Graphics Center

RE: [PATCH v3 2/3] drm/amdgpu_dm: Rely on split out luminance calculation function

[Deucher, Alexander]

[Public]

> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces@lists.freedesktop.org> On Behalf Of Jani
> Nikula
> Sent: Thursday, August 4, 2022 5:55 AM
> To: Jouni Högander <jouni.hogander@intel.com>; dri-
> devel@lists.freedesktop.org; intel-gfx@lists.freedesktop.org; amd-
> gfx@lists.freedesktop.org
> Cc: Siqueira, Rodrigo <Rodrigo.Siqueira@amd.com>; Li, Roman
> <Roman.Li@amd.com>; Manasi Navare <manasi.d.navare@intel.com>; Mika
> Kahola <mika.kahola@intel.com>; Jouni Högander
> <jouni.hogander@intel.com>; Wentland, Harry
> <Harry.Wentland@amd.com>
> Subject: Re: [PATCH v3 2/3] drm/amdgpu_dm: Rely on split out luminance
> calculation function
> 
> On Tue, 19 Jul 2022, Jouni Högander <jouni.hogander@intel.com> wrote:
> > Luminance range calculation was split out into drm_edid.c and is now
> > part of edid parsing. Rely on values calculated during edid parsing
> > and use these for caps->aux_max_input_signal and caps-
> >aux_min_input_signal.
> 
> Harry, I'll merge patches 1 & 3 in this series through drm-misc-next, because I
> think they're good to go, and fix stuff in i915.
> 
> Can I get your rb/ack to merge this patch as well, or do you want to take this
> later via your tree?

You can take this via drm-misc.
Acked-by: Alex Deucher <alexander.deucher@amd.com>


> 
> BR,
> Jani.
> 
> 
> >
> > v2: Use values calculated during edid parsing
> >
> > Cc: Roman Li <roman.li@amd.com>
> > 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>
> > Cc: Manasi Navare <manasi.d.navare@intel.com>
> > Signed-off-by: Jouni Högander <jouni.hogander@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 3e83fed540e8..eb7abdeb8653 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -2903,15 +2903,12 @@ 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_avg, 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};
> > +	struct drm_luminance_range_info *luminance_range;
> >  	int i;
> >
> >  	if (!aconnector || !aconnector->dc_link) @@ -2933,8 +2930,6 @@
> > 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_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 /*||
> >  	    caps->ext_caps->bits.sdr_aux_backlight_control == 1 || @@
> > -2946,31 +2941,9 @@ 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_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);
> > -
> > -	caps->aux_max_input_signal = max;
> > -	caps->aux_min_input_signal = min;
> > +	luminance_range = &conn_base->display_info.luminance_range;
> > +	caps->aux_min_input_signal = luminance_range->min_luminance;
> > +	caps->aux_max_input_signal = luminance_range->max_luminance;
> >  }
> >
> >  void amdgpu_dm_update_connector_after_detect(
> 
> --
> Jani Nikula, Intel Open Source Graphics Center

RE: [PATCH v3 2/3] drm/amdgpu_dm: Rely on split out luminance calculation function

[Jani Nikula]

On Thu, 11 Aug 2022, "Deucher, Alexander" <Alexander.Deucher@amd.com> wrote:
> [Public]
>
>> -----Original Message-----
>> From: amd-gfx <amd-gfx-bounces@lists.freedesktop.org> On Behalf Of Jani
>> Nikula
>> Sent: Thursday, August 4, 2022 5:55 AM
>> To: Jouni Högander <jouni.hogander@intel.com>; dri-
>> devel@lists.freedesktop.org; intel-gfx@lists.freedesktop.org; amd-
>> gfx@lists.freedesktop.org
>> Cc: Siqueira, Rodrigo <Rodrigo.Siqueira@amd.com>; Li, Roman
>> <Roman.Li@amd.com>; Manasi Navare <manasi.d.navare@intel.com>; Mika
>> Kahola <mika.kahola@intel.com>; Jouni Högander
>> <jouni.hogander@intel.com>; Wentland, Harry
>> <Harry.Wentland@amd.com>
>> Subject: Re: [PATCH v3 2/3] drm/amdgpu_dm: Rely on split out luminance
>> calculation function
>> 
>> On Tue, 19 Jul 2022, Jouni Högander <jouni.hogander@intel.com> wrote:
>> > Luminance range calculation was split out into drm_edid.c and is now
>> > part of edid parsing. Rely on values calculated during edid parsing
>> > and use these for caps->aux_max_input_signal and caps-
>> >aux_min_input_signal.
>> 
>> Harry, I'll merge patches 1 & 3 in this series through drm-misc-next, because I
>> think they're good to go, and fix stuff in i915.
>> 
>> Can I get your rb/ack to merge this patch as well, or do you want to take this
>> later via your tree?
>
> You can take this via drm-misc.
> Acked-by: Alex Deucher <alexander.deucher@amd.com>

Thanks, pushed the series to drm-misc-next.

BR,
Jani.

>
>
>> 
>> BR,
>> Jani.
>> 
>> 
>> >
>> > v2: Use values calculated during edid parsing
>> >
>> > Cc: Roman Li <roman.li@amd.com>
>> > 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>
>> > Cc: Manasi Navare <manasi.d.navare@intel.com>
>> > Signed-off-by: Jouni Högander <jouni.hogander@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 3e83fed540e8..eb7abdeb8653 100644
>> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> > @@ -2903,15 +2903,12 @@ 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_avg, 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};
>> > +	struct drm_luminance_range_info *luminance_range;
>> >  	int i;
>> >
>> >  	if (!aconnector || !aconnector->dc_link) @@ -2933,8 +2930,6 @@
>> > 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_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 /*||
>> >  	    caps->ext_caps->bits.sdr_aux_backlight_control == 1 || @@
>> > -2946,31 +2941,9 @@ 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_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);
>> > -
>> > -	caps->aux_max_input_signal = max;
>> > -	caps->aux_min_input_signal = min;
>> > +	luminance_range = &conn_base->display_info.luminance_range;
>> > +	caps->aux_min_input_signal = luminance_range->min_luminance;
>> > +	caps->aux_max_input_signal = luminance_range->max_luminance;
>> >  }
>> >
>> >  void amdgpu_dm_update_connector_after_detect(
>> 
>> --
>> Jani Nikula, Intel Open Source Graphics Center

-- 
Jani Nikula, Intel Open Source Graphics Center