3 files changed, 25 insertions, 0 deletions
diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c b/drivers/gpu/drm/msm/dp/dp_aux.c
index 03f4951c49f4..e67a80d56948 100644
--- a/drivers/gpu/drm/msm/dp/dp_aux.c
+++ b/drivers/gpu/drm/msm/dp/dp_aux.c
@@ -35,6 +35,7 @@ struct dp_aux_private {
 	bool no_send_stop;
 	bool initted;
 	bool is_edp;
+	bool enable_xfers;
 	u32 offset;
 	u32 segment;
 
@@ -302,6 +303,17 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux,
 	}
 
 	/*
+	 * If we're using DP and an external display isn't connected then the
+	 * transfer won't succeed. Return right away. If we don't do this we
+	 * can end up with long timeouts if someone tries to access the DP AUX
+	 * character device when no DP device is connected.
+	 */
+	if (!aux->is_edp && !aux->enable_xfers) {
+		ret = -ENXIO;
+		goto exit;
+	}
+
+	/*
 	 * For eDP it's important to give a reasonably long wait here for HPD
 	 * to be asserted. This is because the panel driver may have _just_
 	 * turned on the panel and then tried to do an AUX transfer. The panel
@@ -433,6 +445,14 @@ irqreturn_t dp_aux_isr(struct drm_dp_aux *dp_aux)
 	return IRQ_HANDLED;
 }
 
+void dp_aux_enable_xfers(struct drm_dp_aux *dp_aux, bool enabled)
+{
+	struct dp_aux_private *aux;
+
+	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);
+	aux->enable_xfers = enabled;
+}
+
 void dp_aux_reconfig(struct drm_dp_aux *dp_aux)
 {
 	struct dp_aux_private *aux;
diff --git a/drivers/gpu/drm/msm/dp/dp_aux.h b/drivers/gpu/drm/msm/dp/dp_aux.h
index 511305da4f66..f3052cb43306 100644
--- a/drivers/gpu/drm/msm/dp/dp_aux.h
+++ b/drivers/gpu/drm/msm/dp/dp_aux.h
@@ -12,6 +12,7 @@
 int dp_aux_register(struct drm_dp_aux *dp_aux);
 void dp_aux_unregister(struct drm_dp_aux *dp_aux);
 irqreturn_t dp_aux_isr(struct drm_dp_aux *dp_aux);
+void dp_aux_enable_xfers(struct drm_dp_aux *dp_aux, bool enabled);
 void dp_aux_init(struct drm_dp_aux *dp_aux);
 void dp_aux_deinit(struct drm_dp_aux *dp_aux);
 void dp_aux_reconfig(struct drm_dp_aux *dp_aux);
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 78464c395c3d..084086033679 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -565,6 +565,8 @@ static int dp_hpd_plug_handle(struct dp_display_private *dp, u32 data)
 	int ret;
 	struct platform_device *pdev = dp->dp_display.pdev;
 
+	dp_aux_enable_xfers(dp->aux, true);
+
 	mutex_lock(&dp->event_mutex);
 
 	state =  dp->hpd_state;
@@ -630,6 +632,8 @@ static int dp_hpd_unplug_handle(struct dp_display_private *dp, u32 data)
 	u32 state;
 	struct platform_device *pdev = dp->dp_display.pdev;
 
+	dp_aux_enable_xfers(dp->aux, false);
+
 	mutex_lock(&dp->event_mutex);
 
 	state = dp->hpd_state;