drm/i915/dp: Sanity check eDP existence

Some hardware claims to have both an LVDS panel and an eDP output.
Whilst this may be true in a rare case, more often it is just broken
hardware. If we see an eDP device we know that it must be connected and
so we can confirm its existence with a simple probe.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=34165
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=24822
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 3216adc..d29e33f 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1856,6 +1856,9 @@ intel_dp_init(struct drm_device *dev, int output_reg)
        if (!intel_dp)
                return;
 
+       intel_dp->output_reg = output_reg;
+       intel_dp->dpms_mode = -1;
+
        intel_connector = kzalloc(sizeof(struct intel_connector), GFP_KERNEL);
        if (!intel_connector) {
                kfree(intel_dp);
@@ -1895,10 +1898,6 @@ intel_dp_init(struct drm_device *dev, int output_reg)
        connector->interlace_allowed = true;
        connector->doublescan_allowed = 0;
 
-       intel_dp->output_reg = output_reg;
-       intel_dp->has_audio = false;
-       intel_dp->dpms_mode = DRM_MODE_DPMS_ON;
-
        drm_encoder_init(dev, &intel_encoder->base, &intel_dp_enc_funcs,
                         DRM_MODE_ENCODER_TMDS);
        drm_encoder_helper_add(&intel_encoder->base, &intel_dp_helper_funcs);
@@ -1951,14 +1950,18 @@ intel_dp_init(struct drm_device *dev, int output_reg)
                ret = intel_dp_aux_native_read(intel_dp, DP_DPCD_REV,
                                               intel_dp->dpcd,
                                               sizeof(intel_dp->dpcd));
+               ironlake_edp_panel_vdd_off(intel_dp);
                if (ret == sizeof(intel_dp->dpcd)) {
                        if (intel_dp->dpcd[0] >= 0x11)
                                dev_priv->no_aux_handshake = intel_dp->dpcd[3] &
                                        DP_NO_AUX_HANDSHAKE_LINK_TRAINING;
                } else {
+                       /* if this fails, presume the device is a ghost */
                        DRM_ERROR("failed to retrieve link info\n");
+                       intel_dp_destroy(&intel_connector->base);
+                       intel_dp_encoder_destroy(&intel_dp->base.base);
+                       return;
                }
-               ironlake_edp_panel_vdd_off(intel_dp);
        }
 
        intel_encoder->hot_plug = intel_dp_hot_plug;