drm/i915: enable scrambling

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.

V3: Addressed review comments from Jani
 - In comments, function names, use "sink" instead of "monitor",
   so that the implementation could be close to the language of
   HDMI spec.

V4: Addressed review comment from Maarten
 - scrambling -> hdmi_scrambling
 - high_tmds_clock_ratio -> hdmi_high_tmds_clock_ratio

V5: Addressed review comments from Ville and Ander
 - Do not modifiy the crtc_state after compute_config. Move all
   scrambling and tmds_clock_ratio calcutations to compute_config.
 - While setting scrambling for source/sink, do not check the
   conditions again, just go by the crtc_state flags. This will
   simplyfy the condition checks.

V6: Addressed review comments from Ville
 - Do not add IS_GLK check in disable/enable function, instead add it
   in compute_config, while setting state flags.
 - Remove unnecessary paranthesis.
 - Simplyfy handle_sink_scrambling function as suggested.
 - Add readout code for scrambling status in get_ddi_config and add a
   check for the same in pipe_config_compare.

V7: Addressed review comments from Ander/Ville
 - No separate function for source scrambling, make it inline
 - Align the last line of the macro TRANS_DDI_HDMI_SCRAMBLING_MASK
 - Do not add platform check while setting source scrambling
 - Use pipe_config instead of crtc->config to set sink scrambling
 - To readout scrambling status, Compare with SCRAMBLING_MASK
   not any of its bits
 - Remove platform check in intel_pipe_config_compare while checking
   scrambling status

V8: Fixed mege conflict, Addressed review comments from Ander
 - Remove the desciption/comment about scrambling fom the caller, move
   it to the function
 - Move the IS_GLK check into scrambling function
 - Fix alignment

V9: Fixed review comments from Ville, Ander
 - Pass the scrambling state variables as bool input to the sink_scrambling
   function and let the disable call be unconditional.
 - Fix alignments in function calls and debug messages.
 - Add kernel doc for function intel_hdmi_handle_sink_scrambling

V10: Rebase

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1489404244-16608-6-git-send-email-shashank.sharma@intel.com

1 files changed, 63 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 3eec74c..e0bdc19 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>
@@ -1334,6 +1335,7 @@ bool intel_hdmi_compute_config(struct intel_encoder *encoder,
 	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&encoder->base);
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
+	struct drm_scdc *scdc = &conn_state->connector->display_info.hdmi.scdc;
 	int clock_8bpc = pipe_config->base.adjusted_mode.crtc_clock;
 	int clock_12bpc = clock_8bpc * 3 / 2;
 	int desired_bpp;
@@ -1403,6 +1405,16 @@ bool intel_hdmi_compute_config(struct intel_encoder *encoder,
 
 	pipe_config->lane_count = 4;
 
+	if (scdc->scrambling.supported && IS_GEMINILAKE(dev_priv)) {
+		if (scdc->scrambling.low_rates)
+			pipe_config->hdmi_scrambling = true;
+
+		if (pipe_config->port_clock > 340000) {
+			pipe_config->hdmi_scrambling = true;
+			pipe_config->hdmi_high_tmds_clock_ratio = true;
+		}
+	}
+
 	return true;
 }
 
@@ -1812,6 +1824,57 @@ intel_hdmi_add_properties(struct intel_hdmi *intel_hdmi, struct drm_connector *c
 	intel_hdmi->aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
 }
 
+/*
+ * intel_hdmi_handle_sink_scrambling: handle sink scrambling/clock ratio setup
+ * @encoder: intel_encoder
+ * @connector: drm_connector
+ * @high_tmds_clock_ratio = bool to indicate if the function needs to set
+ *  or reset the high tmds clock ratio for scrambling
+ * @scrambling: bool to Indicate if the function needs to set or reset
+ *  sink scrambling
+ *
+ * This function handles scrambling on HDMI 2.0 capable sinks.
+ * If required clock rate is > 340 Mhz && scrambling is supported by sink
+ * it enables scrambling. This should be called before enabling the HDMI
+ * 2.0 port, as the sink can choose to disable the scrambling if it doesn't
+ * detect a scrambled clock within 100 ms.
+ */
+void intel_hdmi_handle_sink_scrambling(struct intel_encoder *encoder,
+				       struct drm_connector *connector,
+				       bool high_tmds_clock_ratio,
+				       bool scrambling)
+{
+	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&encoder->base);
+	struct drm_i915_private *dev_priv = connector->dev->dev_private;
+	struct drm_scrambling *sink_scrambling =
+				&connector->display_info.hdmi.scdc.scrambling;
+	struct i2c_adapter *adptr = intel_gmbus_get_adapter(dev_priv,
+							   intel_hdmi->ddc_bus);
+	bool ret;
+
+	if (!sink_scrambling->supported)
+		return;
+
+	DRM_DEBUG_KMS("Setting sink scrambling for enc:%s connector:%s\n",
+		      encoder->base.name, connector->name);
+
+	/* Set TMDS bit clock ratio to 1/40 or 1/10 */
+	ret = drm_scdc_set_high_tmds_clock_ratio(adptr, high_tmds_clock_ratio);
+	if (!ret) {
+		DRM_ERROR("Set TMDS ratio failed\n");
+		return;
+	}
+
+	/* Enable/disable sink scrambling */
+	ret = drm_scdc_set_scrambling(adptr, scrambling);
+	if (!ret) {
+		DRM_ERROR("Set sink scrambling failed\n");
+		return;
+	}
+
+	DRM_DEBUG_KMS("sink scrambling handled\n");
+}
+
 static u8 intel_hdmi_ddc_pin(struct drm_i915_private *dev_priv,
 			     enum port port)
 {