[Intel-gfx] [PATCH] drm/i915: make sure panel is on for eDP detection

[Jesse Barnes]

DP AUX transactions on the panel won't work unless the panel is
powered.   This patch also fixes a merge error that snuck into the DP
prepare function; we need to power on the panel for both CPU and PCH
attached panels.

Signed-off-by: Jesse Barnes <jbar...@virtuousgeek.org>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 9caccd0..668d0da 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -756,13 +756,14 @@ intel_dp_mode_set(struct drm_encoder *encoder, struct 
drm_display_mode *mode,
        }
 }
 
-static void ironlake_edp_panel_on (struct drm_device *dev)
+/* Returns true if the panel was already on when called */
+static bool ironlake_edp_panel_on (struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 pp;
 
        if (I915_READ(PCH_PP_STATUS) & PP_ON)
-               return;
+               return true;
 
        pp = I915_READ(PCH_PP_CONTROL);
 
@@ -782,6 +783,8 @@ static void ironlake_edp_panel_on (struct drm_device *dev)
        pp |= PANEL_POWER_RESET; /* restore panel reset bit */
        I915_WRITE(PCH_PP_CONTROL, pp);
        POSTING_READ(PCH_PP_CONTROL);
+
+       return false;
 }
 
 static void ironlake_edp_panel_off (struct drm_device *dev)
@@ -862,7 +865,7 @@ static void intel_dp_prepare(struct drm_encoder *encoder)
        struct drm_i915_private *dev_priv = dev->dev_private;
        uint32_t dp_reg = I915_READ(intel_dp->output_reg);
 
-       if (IS_eDP(intel_dp)) {
+       if (IS_eDP(intel_dp) || IS_PCH_eDP(intel_dp)) {
                ironlake_edp_backlight_off(dev);
                ironlake_edp_panel_on(dev);
                ironlake_edp_pll_on(encoder);
@@ -1367,7 +1370,11 @@ ironlake_dp_detect(struct drm_connector *connector)
        struct drm_encoder *encoder = intel_attached_encoder(connector);
        struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
        enum drm_connector_status status;
+       bool was_on = false;
 
+       /* Panel needs power for AUX to work */
+       if (IS_eDP(intel_dp) || IS_PCH_eDP(intel_dp))
+               was_on = ironlake_edp_panel_on(connector->dev);
        status = connector_status_disconnected;
        if (intel_dp_aux_native_read(intel_dp,
                                     0x000, intel_dp->dpcd,
@@ -1378,6 +1385,8 @@ ironlake_dp_detect(struct drm_connector *connector)
        }
        DRM_DEBUG_KMS("DPCD: %hx%hx%hx%hx\n", intel_dp->dpcd[0],
                      intel_dp->dpcd[1], intel_dp->dpcd[2], intel_dp->dpcd[3]);
+       if ((IS_eDP(intel_dp) || IS_PCH_eDP(intel_dp)) && !was_on)
+               ironlake_edp_panel_off(connector->dev);
        return status;
 }
 

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