[PATCH v2 5/6] drm/i915: enable scrambling

[Shashank Sharma <shashank.sharma@intel.com>]

Geminilake platform sports a native HDMI 2.0 controller, and is
capable of driving pixel-clocks upto 594Mhz. HDMI 2.0 spec
mendates scrambling for these higher clocks, for reduced RF footprint.

This patch checks if the monitor supports scrambling, and if required,
enables it during the modeset.

V2: Addressed review comments from Ville:
- Do not track scrambling status in DRM layer, track somewhere in
  driver like in intel_crtc_state.
- Don't talk to monitor at such a low layer, set monitor scrambling
  in intel_enable_ddi() before enabling the port.

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h   |  2 ++
 drivers/gpu/drm/i915/intel_ddi.c  | 26 +++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h  | 11 ++++++
 drivers/gpu/drm/i915/intel_hdmi.c | 70 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 109 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 495b789..cc85892 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7807,6 +7807,8 @@ enum {
 #define  TRANS_DDI_EDP_INPUT_C_ONOFF	(6<<12)
 #define  TRANS_DDI_DP_VC_PAYLOAD_ALLOC	(1<<8)
 #define  TRANS_DDI_BFI_ENABLE		(1<<4)
+#define  TRANS_DDI_HIGH_TMDS_CHAR_RATE	(1<<4)
+#define  TRANS_DDI_HDMI_SCRAMBLING	(1<<0)
 
 /* DisplayPort Transport Control */
 #define _DP_TP_CTL_A			0x64040
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 9a9a670..cc7e091 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1278,6 +1278,11 @@ void intel_ddi_enable_transcoder_func(struct drm_crtc *crtc)
 			temp |= TRANS_DDI_MODE_SELECT_HDMI;
 		else
 			temp |= TRANS_DDI_MODE_SELECT_DVI;
+
+		if (IS_GEMINILAKE(dev_priv))
+			temp = intel_hdmi_handle_source_scrambling(
+				intel_encoder,
+				&intel_crtc->config->base.adjusted_mode, temp);
 	} else if (type == INTEL_OUTPUT_ANALOG) {
 		temp |= TRANS_DDI_MODE_SELECT_FDI;
 		temp |= (intel_crtc->config->fdi_lanes - 1) << 1;
@@ -1845,6 +1850,21 @@ static void intel_enable_ddi(struct intel_encoder *intel_encoder,
 		struct intel_digital_port *intel_dig_port =
 			enc_to_dig_port(encoder);
 
+		if (IS_GEMINILAKE(dev_priv)) {
+			/*
+			 * GLK sports a native HDMI 2.0 controller. If required
+			 * clock rate is > 340 Mhz && scrambling is supported
+			 * by monitor, enable scrambling before enabling the
+			 * HDMI 2.0 port. The sink can choose to disable the
+			 * scrambling if it doesn't detect a scrambled within
+			 * 100 ms.
+			 */
+			intel_hdmi_handle_monitor_scrambling(intel_encoder,
+							conn_state->connector,
+							intel_crtc->config,
+							true);
+		}
+
 		/* In HDMI/DVI mode, the port width, and swing/emphasis values
 		 * are ignored so nothing special needs to be done besides
 		 * enabling the port.
@@ -1885,6 +1905,12 @@ static void intel_disable_ddi(struct intel_encoder *intel_encoder,
 		intel_display_power_put(dev_priv, POWER_DOMAIN_AUDIO);
 	}
 
+	if (type == INTEL_OUTPUT_HDMI) {
+		intel_hdmi_handle_monitor_scrambling(intel_encoder,
+						old_conn_state->connector,
+						intel_crtc->config, false);
+	}
+
 	if (type == INTEL_OUTPUT_EDP) {
 		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 393f243..300353c 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -681,6 +681,9 @@ struct intel_crtc_state {
 
 	/* Gamma mode programmed on the pipe */
 	uint32_t gamma_mode;
+
+	/* HDMI scrambling status (monitor) */
+	bool scrambling;
 };
 
 struct vlv_wm_state {
@@ -1588,6 +1591,14 @@ void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
 bool intel_hdmi_compute_config(struct intel_encoder *encoder,
 			       struct intel_crtc_state *pipe_config,
 			       struct drm_connector_state *conn_state);
+uint32_t
+intel_hdmi_handle_source_scrambling(struct intel_encoder *intel_encoder,
+					struct drm_display_mode *mode,
+					uint32_t config);
+void intel_hdmi_handle_monitor_scrambling(struct intel_encoder *intel_encoder,
+					struct drm_connector *connector,
+					struct intel_crtc_state *config,
+					bool enable);
 void intel_dp_dual_mode_set_tmds_output(struct intel_hdmi *hdmi, bool enable);
 
 
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index ebae2bd..41d3309 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -34,6 +34,7 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_edid.h>
+#include <drm/drm_scdc_helper.h>
 #include "intel_drv.h"
 #include <drm/i915_drm.h>
 #include <drm/intel_lpe_audio.h>
@@ -1795,6 +1796,75 @@ static void intel_hdmi_destroy(struct drm_connector *connector)
 	intel_hdmi->aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
 }
 
+void intel_hdmi_handle_monitor_scrambling(struct intel_encoder *intel_encoder,
+				       struct drm_connector *connector,
+				       struct intel_crtc_state *config,
+				       bool enable)
+{
+	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&intel_encoder->base);
+	struct drm_scdc *scdc = &connector->display_info.hdmi.scdc;
+	struct drm_scrambling *scrambling = &scdc->scrambling;
+	struct drm_display_mode *mode = &config->base.adjusted_mode;
+	struct drm_i915_private *dev_priv = connector->dev->dev_private;
+	struct i2c_adapter *adptr = intel_gmbus_get_adapter(dev_priv,
+							  intel_hdmi->ddc_bus);
+
+	if (!scrambling->supported)
+		return;
+
+	DRM_DEBUG_KMS("Setting monitor scrambling for enc:%s connector:%s\n",
+			intel_encoder->base.name, connector->name);
+
+	/* Enable monitor scrambling */
+	if (enable) {
+		if (mode->clock > 340000 || scrambling->low_rates) {
+			config->scrambling = drm_scdc_enable_scrambling(adptr);
+			if (!config->scrambling)
+				DRM_ERROR("Can't enable monitor scrambling\n");
+		}
+		return;
+	}
+
+	/* Disable monitor scrambling */
+	if (config->scrambling) {
+		config->scrambling = !(drm_scdc_disable_scrambling(adptr));
+		if (config->scrambling)
+			DRM_ERROR("Can't disable monitor scrambling\n");
+	}
+
+}
+
+uint32_t
+intel_hdmi_handle_source_scrambling(struct intel_encoder *intel_encoder,
+			struct drm_display_mode *mode, uint32_t hdmi_config)
+{
+	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&intel_encoder->base);
+	struct drm_connector *connector = &intel_hdmi->attached_connector->base;
+	struct drm_hdmi_info *hdmi_info = &connector->display_info.hdmi;
+	struct drm_scrambling *scrambling = &hdmi_info->scdc.scrambling;
+
+	DRM_DEBUG_KMS("Setting scrambling for enc:%s connector:%s\n",
+			intel_encoder->base.name, connector->name);
+
+	hdmi_config &= ~TRANS_DDI_HDMI_SCRAMBLING;
+	hdmi_config &= ~TRANS_DDI_HIGH_TMDS_CHAR_RATE;
+
+	if (mode->clock <= 340000) {
+		/* Few sinks support scrambling at rate < 340 MHz too */
+		if (scrambling->low_rates)
+			hdmi_config |= TRANS_DDI_HDMI_SCRAMBLING;
+		return hdmi_config;
+	}
+
+	/* Scrambling or not, if clock > 340 MHz, set high char rate */
+	hdmi_config |= TRANS_DDI_HIGH_TMDS_CHAR_RATE;
+
+	if (scrambling->supported)
+		hdmi_config |= TRANS_DDI_HDMI_SCRAMBLING;
+
+	return hdmi_config;
+}
+
 static u8 intel_hdmi_ddc_pin(struct drm_i915_private *dev_priv,
 			     enum port port)
 {
-- 
1.9.1

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