drm: Use a nondestructive mode for output detect when polling

Destructive load-detection is very expensive and due to failings
elsewhere can trigger system wide stalls of up to 600ms. A simple
first step to correcting this is not to invoke such an expensive
and destructive load-detection operation automatically.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29536
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=16265
Reported-by: Bruno Prémont <bonbons@linux-vserver.org>
Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_crtc_helper.c

@@ -103,7 +103,7 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 		if (connector->funcs->force)
 			connector->funcs->force(connector);
 	} else {
-		connector->status = connector->funcs->detect(connector);
+		connector->status = connector->funcs->detect(connector, false);
 		drm_kms_helper_poll_enable(dev);
 	}
 
@@ -866,7 +866,7 @@ static void output_poll_execute(struct work_struct *work)
 		    !(connector->polled & DRM_CONNECTOR_POLL_HPD))
 			continue;
 
-		status = connector->funcs->detect(connector);
+		status = connector->funcs->detect(connector, true);
 		if (old_status != status)
 			changed = true;
 	}

drivers/gpu/drm/drm_sysfs.c

@@ -159,7 +159,7 @@ static ssize_t status_show(struct device *device,
 	struct drm_connector *connector = to_drm_connector(device);
 	enum drm_connector_status status;
 
-	status = connector->funcs->detect(connector);
+	status = connector->funcs->detect(connector, true);
 	return snprintf(buf, PAGE_SIZE, "%s\n",
 			drm_get_connector_status_name(status));
 }

drivers/gpu/drm/i915/intel_crt.c

@@ -400,7 +400,9 @@ intel_crt_load_detect(struct drm_crtc *crtc, struct intel_encoder *intel_encoder
 	return status;
 }
 
-static enum drm_connector_status intel_crt_detect(struct drm_connector *connector)
+static enum drm_connector_status
+intel_crt_detect(struct drm_connector *connector,
+		 bool nondestructive)
 {
 	struct drm_device *dev = connector->dev;
 	struct drm_encoder *encoder = intel_attached_encoder(connector);
@@ -419,6 +421,9 @@ static enum drm_connector_status intel_crt_detect(struct drm_connector *connecto
 	if (intel_crt_detect_ddc(encoder))
 		return connector_status_connected;
 
+	if (nondestructive)
+		return connector->status;
+
 	/* for pre-945g platforms use load detect */
 	if (encoder->crtc && encoder->crtc->enabled) {
 		status = intel_crt_load_detect(encoder->crtc, intel_encoder);

drivers/gpu/drm/i915/intel_dp.c

@@ -1386,7 +1386,8 @@ ironlake_dp_detect(struct drm_connector *connector)
  * \return false if DP port is disconnected.
  */
 static enum drm_connector_status
-intel_dp_detect(struct drm_connector *connector)
+intel_dp_detect(struct drm_connector *connector,
+		bool nondestructive)
 {
 	struct drm_encoder *encoder = intel_attached_encoder(connector);
 	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);

drivers/gpu/drm/i915/intel_dvo.c

@@ -221,7 +221,9 @@ static void intel_dvo_mode_set(struct drm_encoder *encoder,
  *
  * Unimplemented.
  */
-static enum drm_connector_status intel_dvo_detect(struct drm_connector *connector)
+static enum drm_connector_status
+intel_dvo_detect(struct drm_connector *connector,
+		 bool nondestructive)
 {
 	struct drm_encoder *encoder = intel_attached_encoder(connector);
 	struct intel_dvo *intel_dvo = enc_to_intel_dvo(encoder);

drivers/gpu/drm/i915/intel_hdmi.c

@@ -139,7 +139,8 @@ static bool intel_hdmi_mode_fixup(struct drm_encoder *encoder,
 }
 
 static enum drm_connector_status
-intel_hdmi_detect(struct drm_connector *connector)
+intel_hdmi_detect(struct drm_connector *connector,
+		  bool nondestructive)
 {
 	struct drm_encoder *encoder = intel_attached_encoder(connector);
 	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(encoder);

drivers/gpu/drm/i915/intel_lvds.c

@@ -445,7 +445,9 @@ static void intel_lvds_mode_set(struct drm_encoder *encoder,
  * connected and closed means disconnected.  We also send hotplug events as
  * needed, using lid status notification from the input layer.
  */
-static enum drm_connector_status intel_lvds_detect(struct drm_connector *connector)
+static enum drm_connector_status
+intel_lvds_detect(struct drm_connector *connector,
+		  bool nondestructive)
 {
 	struct drm_device *dev = connector->dev;
 	enum drm_connector_status status = connector_status_connected;
@@ -540,7 +542,9 @@ static int intel_lid_notify(struct notifier_block *nb, unsigned long val,
 	 * the LID nofication event.
 	 */
 	if (connector)
-		connector->status = connector->funcs->detect(connector);
+		connector->status = connector->funcs->detect(connector,
+							     true);
+
 	/* Don't force modeset on machines where it causes a GPU lockup */
 	if (dmi_check_system(intel_no_modeset_on_lid))
 		return NOTIFY_OK;

drivers/gpu/drm/i915/intel_sdvo.c

@@ -1417,7 +1417,7 @@ intel_analog_is_connected(struct drm_device *dev)
 	if (!analog_connector)
 		return false;
 
-	if (analog_connector->funcs->detect(analog_connector) ==
+	if (analog_connector->funcs->detect(analog_connector, true) ==
 			connector_status_disconnected)
 		return false;
 
@@ -1486,7 +1486,9 @@ intel_sdvo_hdmi_sink_detect(struct drm_connector *connector)
 	return status;
 }
 
-static enum drm_connector_status intel_sdvo_detect(struct drm_connector *connector)
+static enum drm_connector_status
+intel_sdvo_detect(struct drm_connector *connector,
+		  bool nondestructive)
 {
 	uint16_t response;
 	struct drm_encoder *encoder = intel_attached_encoder(connector);

drivers/gpu/drm/i915/intel_tv.c

@@ -1341,7 +1341,8 @@ static void intel_tv_find_better_format(struct drm_connector *connector)
  * we have a pipe programmed in order to probe the TV.
  */
 static enum drm_connector_status
-intel_tv_detect(struct drm_connector *connector)
+intel_tv_detect(struct drm_connector *connector,
+		bool nondestructive)
 {
 	struct drm_display_mode mode;
 	struct drm_encoder *encoder = intel_attached_encoder(connector);
@@ -1353,7 +1354,7 @@ intel_tv_detect(struct drm_connector *connector)
 
 	if (encoder->crtc && encoder->crtc->enabled) {
 		type = intel_tv_detect_type(intel_tv);
-	} else {
+	} else if (nondestructive) {
 		struct drm_crtc *crtc;
 		int dpms_mode;
 
@@ -1364,10 +1365,9 @@ intel_tv_detect(struct drm_connector *connector)
 			intel_release_load_detect_pipe(&intel_tv->base, connector,
 						       dpms_mode);
 		} else
-			type = -1;
-	}
-
-	intel_tv->type = type;
+			return connector_status_unknown;
+	} else
+		return connector->status;
 
 	if (type < 0)
 		return connector_status_disconnected;

drivers/gpu/drm/nouveau/nouveau_connector.c

@@ -168,7 +168,8 @@ nouveau_connector_set_encoder(struct drm_connector *connector,
 }
 
 static enum drm_connector_status
-nouveau_connector_detect(struct drm_connector *connector)
+nouveau_connector_detect(struct drm_connector *connector,
+			 bool nondestructive)
 {
 	struct drm_device *dev = connector->dev;
 	struct nouveau_connector *nv_connector = nouveau_connector(connector);
@@ -246,7 +247,8 @@ nouveau_connector_detect(struct drm_connector *connector)
 }
 
 static enum drm_connector_status
-nouveau_connector_detect_lvds(struct drm_connector *connector)
+nouveau_connector_detect_lvds(struct drm_connector *connector,
+			      bool nondestructive)
 {
 	struct drm_device *dev = connector->dev;
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
@@ -267,7 +269,7 @@ nouveau_connector_detect_lvds(struct drm_connector *connector)
 
 	/* Try retrieving EDID via DDC */
 	if (!dev_priv->vbios.fp_no_ddc) {
-		status = nouveau_connector_detect(connector);
+		status = nouveau_connector_detect(connector, nondestructive);
 		if (status == connector_status_connected)
 			goto out;
 	}

drivers/gpu/drm/radeon/radeon_connectors.c

@@ -481,7 +481,9 @@ static int radeon_lvds_mode_valid(struct drm_connector *connector,
 	return MODE_OK;
 }
 
-static enum drm_connector_status radeon_lvds_detect(struct drm_connector *connector)
+static enum drm_connector_status
+radeon_lvds_detect(struct drm_connector *connector,
+		   bool nondestructive)
 {
 	struct radeon_connector *radeon_connector = to_radeon_connector(connector);
 	struct drm_encoder *encoder = radeon_best_single_encoder(connector);
@@ -594,7 +596,9 @@ static int radeon_vga_mode_valid(struct drm_connector *connector,
 	return MODE_OK;
 }
 
-static enum drm_connector_status radeon_vga_detect(struct drm_connector *connector)
+static enum drm_connector_status
+radeon_vga_detect(struct drm_connector *connector,
+		  bool nondestructive)
 {
 	struct radeon_connector *radeon_connector = to_radeon_connector(connector);
 	struct drm_encoder *encoder;
@@ -691,7 +695,9 @@ static int radeon_tv_mode_valid(struct drm_connector *connector,
 	return MODE_OK;
 }
 
-static enum drm_connector_status radeon_tv_detect(struct drm_connector *connector)
+static enum drm_connector_status
+radeon_tv_detect(struct drm_connector *connector,
+		 bool nondestructive)
 {
 	struct drm_encoder *encoder;
 	struct drm_encoder_helper_funcs *encoder_funcs;
@@ -748,7 +754,9 @@ static int radeon_dvi_get_modes(struct drm_connector *connector)
  * we have to check if this analog encoder is shared with anyone else (TV)
  * if its shared we have to set the other connector to disconnected.
  */
-static enum drm_connector_status radeon_dvi_detect(struct drm_connector *connector)
+static enum drm_connector_status
+radeon_dvi_detect(struct drm_connector *connector,
+		  bool nondestructive)
 {
 	struct radeon_connector *radeon_connector = to_radeon_connector(connector);
 	struct drm_encoder *encoder = NULL;
@@ -972,7 +980,9 @@ static int radeon_dp_get_modes(struct drm_connector *connector)
 	return ret;
 }
 
-static enum drm_connector_status radeon_dp_detect(struct drm_connector *connector)
+static enum drm_connector_status
+radeon_dp_detect(struct drm_connector *connector,
+		 bool nondestructive)
 {
 	struct radeon_connector *radeon_connector = to_radeon_connector(connector);
 	enum drm_connector_status ret = connector_status_disconnected;

drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c

@@ -335,7 +335,8 @@ static void vmw_ldu_connector_restore(struct drm_connector *connector)
 }
 
 static enum drm_connector_status
-	vmw_ldu_connector_detect(struct drm_connector *connector)
+	vmw_ldu_connector_detect(struct drm_connector *connector,
+				 bool nondestructive)
 {
 	if (vmw_connector_to_ldu(connector)->pref_active)
 		return connector_status_connected;

include/drm/drm_crtc.h

@@ -386,7 +386,8 @@ struct drm_connector_funcs {
 	void (*dpms)(struct drm_connector *connector, int mode);
 	void (*save)(struct drm_connector *connector);
 	void (*restore)(struct drm_connector *connector);
-	enum drm_connector_status (*detect)(struct drm_connector *connector);
+	enum drm_connector_status (*detect)(struct drm_connector *connector,
+					    bool nondestructive);
 	int (*fill_modes)(struct drm_connector *connector, uint32_t max_width, uint32_t max_height);
 	int (*set_property)(struct drm_connector *connector, struct drm_property *property,
 			     uint64_t val);