[PATCH 3/4] drm/i915: Enable/disable TMDS output buffers in DP++ adaptor as needed

[ville.syrj...@linux.intel.com]

From: Ville Syrjälä <ville.syrj...@linux.intel.com>

To save a bit of power, let's try to turn off the TMDS output buffers
in DP++ adaptors when we're not driving the port.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_drv.h  |  1 +
 drivers/gpu/drm/i915/intel_hdmi.c | 27 +++++++++++++++++++++++++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 944eacbfb6a9..3ca29a181e64 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -706,6 +706,7 @@ struct intel_hdmi {
        int ddc_bus;
        struct {
                int max_tmds_clock;
+               bool tmds_output_control;
        } dp_dual_mode;
        bool limited_color_range;
        bool color_range_auto;
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c 
b/drivers/gpu/drm/i915/intel_hdmi.c
index 1e8cfdb18dc7..660a65f48fd8 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -846,6 +846,13 @@ static void intel_hdmi_prepare(struct intel_encoder 
*encoder)
        const struct drm_display_mode *adjusted_mode = 
&crtc->config->base.adjusted_mode;
        u32 hdmi_val;

+       if (intel_hdmi->dp_dual_mode.tmds_output_control) {
+               struct i2c_adapter *adapter =
+                       intel_gmbus_get_adapter(dev_priv, intel_hdmi->ddc_bus);
+
+               drm_dp_dual_mode_set_tmds_output(adapter, true);
+       }
+
        hdmi_val = SDVO_ENCODING_HDMI;
        if (!HAS_PCH_SPLIT(dev) && crtc->config->limited_color_range)
                hdmi_val |= HDMI_COLOR_RANGE_16_235;
@@ -1144,6 +1151,13 @@ static void intel_disable_hdmi(struct intel_encoder 
*encoder)
        }

        intel_hdmi->set_infoframes(&encoder->base, false, NULL);
+
+       if (intel_hdmi->dp_dual_mode.tmds_output_control) {
+               struct i2c_adapter *adapter =
+                       intel_gmbus_get_adapter(dev_priv, intel_hdmi->ddc_bus);
+
+               drm_dp_dual_mode_set_tmds_output(adapter, false);
+       }
 }

 static void g4x_disable_hdmi(struct intel_encoder *encoder)
@@ -1369,6 +1383,7 @@ intel_hdmi_unset_edid(struct drm_connector *connector)
        intel_hdmi->rgb_quant_range_selectable = false;

        intel_hdmi->dp_dual_mode.max_tmds_clock = 0;
+       intel_hdmi->dp_dual_mode.tmds_output_control = false;

        kfree(to_intel_connector(connector)->detect_edid);
        to_intel_connector(connector)->detect_edid = NULL;
@@ -1392,15 +1407,23 @@ intel_hdmi_dp_dual_mode_detect(struct drm_connector 
*connector)
         */
        if (type == DRM_DP_DUAL_MODE_TYPE2_DVI ||
            type == DRM_DP_DUAL_MODE_TYPE2_HDMI) {
+               bool tmds_enabled;
+
                hdmi->dp_dual_mode.max_tmds_clock =
                        drm_dp_dual_mode_max_tmds_clock(adapter);
+
+               hdmi->dp_dual_mode.tmds_output_control =
+                       drm_dp_dual_mode_get_tmds_output(adapter, 
&tmds_enabled) == 0 &&
+                       drm_dp_dual_mode_set_tmds_output(adapter, tmds_enabled) 
== 0;
        } else {
                hdmi->dp_dual_mode.max_tmds_clock = 165000;
+               hdmi->dp_dual_mode.tmds_output_control = false;
        }

-       DRM_DEBUG_KMS("DP dual mode adaptor (%s) detected (max TMDS clock: %d 
kHz)\n",
+       DRM_DEBUG_KMS("DP dual mode adaptor (%s) detected (max TMDS clock: %d 
kHz, TMDS OE# control: %s)\n",
                      drm_dp_get_dual_mode_type_name(type),
-                     hdmi->dp_dual_mode.max_tmds_clock);
+                     hdmi->dp_dual_mode.max_tmds_clock,
+                     yesno(hdmi->dp_dual_mode.tmds_output_control));
 }

 static bool
-- 
2.4.10