[Intel-gfx] [PATCH] drm/i915/hdmi: Initialize SCDC registers according to spec

[clinton.a.taylor at intel.com]

From: Clint Taylor <clinton.a.taylor at intel.com>

Initialize SCDC Source Version and TDMS_Config_0 registers to nominal
values during intel_hdmi_detect(). The i915 driver currently doesn't
implement features that require polling of the status update bits. Once
FRL, DSC, or Source Test is enabled in the driver the status flags will
need to be read by the source according to specification.

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Clint Taylor <clinton.a.taylor at intel.com>
---
 drivers/gpu/drm/i915/intel_hdmi.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 2c53efc..ab3eac5 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1910,6 +1910,8 @@ bool intel_hdmi_compute_config(struct intel_encoder *encoder,
 	struct drm_i915_private *dev_priv = to_i915(connector->dev);
 	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
 	struct intel_encoder *encoder = &hdmi_to_dig_port(intel_hdmi)->base;
+	struct i2c_adapter *adapter =
+		intel_gmbus_get_adapter(dev_priv, intel_hdmi->ddc_bus);
 
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
 		      connector->base.id, connector->name);
@@ -1925,6 +1927,16 @@ bool intel_hdmi_compute_config(struct intel_encoder *encoder,
 	if (intel_hdmi_set_edid(connector))
 		status = connector_status_connected;
 
+	if (connector->display_info.hdmi.scdc.supported) {
+		/* SCDC source version HDMI 2.1 Sec. 10.4.1.2 */
+		if (drm_scdc_writeb(adapter, SCDC_SOURCE_VERSION, 0x01) < 0)
+			DRM_DEBUG_KMS("Unable to set SCDC Source Version register\n");
+
+		/* Clear SCDC CONFIG_0 HDMI 2.1 Sec. 10.4.1.6 - RR_Enable Polling Only */
+		if (drm_scdc_writeb(adapter, SCDC_CONFIG_0, 0x00) < 0)
+			DRM_DEBUG_KMS("Unable to set SCDC CONFIG_0 register\n");
+	}
+
 out:
 	intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
 
-- 
1.9.1