drm/i915/dp: manage sink power state if possible

On sinks with a DPCD rev of 1.1 or greater, we can send sink power
management commands to address 0x600 per section 5.1.5 of the
DisplayPort 1.1a spec.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index bca48b0..e2aced6 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -942,11 +942,44 @@ static void ironlake_edp_pll_off(struct drm_encoder *encoder)
        udelay(200);
 }
 
+/* If the sink supports it, try to set the power state appropriately */
+static void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode)
+{
+       int ret, i;
+
+       /* Should have a valid DPCD by this point */
+       if (intel_dp->dpcd[DP_DPCD_REV] < 0x11)
+               return;
+
+       if (mode != DRM_MODE_DPMS_ON) {
+               ret = intel_dp_aux_native_write_1(intel_dp, DP_SET_POWER,
+                                                 DP_SET_POWER_D3);
+               if (ret != 1)
+                       DRM_DEBUG_DRIVER("failed to write sink power state\n");
+       } else {
+               /*
+                * When turning on, we need to retry for 1ms to give the sink
+                * time to wake up.
+                */
+               for (i = 0; i < 3; i++) {
+                       ret = intel_dp_aux_native_write_1(intel_dp,
+                                                         DP_SET_POWER,
+                                                         DP_SET_POWER_D0);
+                       if (ret == 1)
+                               break;
+                       msleep(1);
+               }
+       }
+}
+
 static void intel_dp_prepare(struct drm_encoder *encoder)
 {
        struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
        struct drm_device *dev = encoder->dev;
 
+       /* Wake up the sink first */
+       intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
+
        if (is_edp(intel_dp)) {
                ironlake_edp_backlight_off(dev);
                ironlake_edp_panel_off(dev);
@@ -990,6 +1023,7 @@ intel_dp_dpms(struct drm_encoder *encoder, int mode)
        if (mode != DRM_MODE_DPMS_ON) {
                if (is_edp(intel_dp))
                        ironlake_edp_backlight_off(dev);
+               intel_dp_sink_dpms(intel_dp, mode);
                intel_dp_link_down(intel_dp);
                if (is_edp(intel_dp))
                        ironlake_edp_panel_off(dev);
@@ -998,6 +1032,7 @@ intel_dp_dpms(struct drm_encoder *encoder, int mode)
        } else {
                if (is_edp(intel_dp))
                        ironlake_edp_panel_vdd_on(intel_dp);
+               intel_dp_sink_dpms(intel_dp, mode);
                if (!(dp_reg & DP_PORT_EN)) {
                        intel_dp_start_link_train(intel_dp);
                        if (is_edp(intel_dp)) {