OMAP: DSS2: check for manager when enabling display

None of the DSS interface drivers check if an overlay manager is
connected to the display when the display is being enabled. This leads
to null pointer crash if the display has no manager.

This patch checks for the manager and returns an error if it is null.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/dpi.c

@@ -176,6 +176,11 @@ int omapdss_dpi_display_enable(struct omap_dss_device *dssdev)
 {
 	int r;
 
+	if (dssdev->manager == NULL) {
+		DSSERR("failed to enable display: no manager\n");
+		return -ENODEV;
+	}
+
 	r = omap_dss_start_device(dssdev);
 	if (r) {
 		DSSERR("failed to start device\n");

drivers/video/omap2/dss/dsi.c

@@ -4211,6 +4211,12 @@ int omapdss_dsi_display_enable(struct omap_dss_device *dssdev)
 
 	mutex_lock(&dsi->lock);
 
+	if (dssdev->manager == NULL) {
+		DSSERR("failed to enable display: no manager\n");
+		r = -ENODEV;
+		goto err_start_dev;
+	}
+
 	r = omap_dss_start_device(dssdev);
 	if (r) {
 		DSSERR("failed to start device\n");

drivers/video/omap2/dss/hdmi.c

@@ -1231,6 +1231,12 @@ int omapdss_hdmi_display_enable(struct omap_dss_device *dssdev)
 
 	mutex_lock(&hdmi.lock);
 
+	if (dssdev->manager == NULL) {
+		DSSERR("failed to enable display: no manager\n");
+		r = -ENODEV;
+		goto err0;
+	}
+
 	r = omap_dss_start_device(dssdev);
 	if (r) {
 		DSSERR("failed to start device\n");

drivers/video/omap2/dss/rfbi.c

@@ -860,6 +860,11 @@ int omapdss_rfbi_display_enable(struct omap_dss_device *dssdev)
 {
 	int r;
 
+	if (dssdev->manager == NULL) {
+		DSSERR("failed to enable display: no manager\n");
+		return -ENODEV;
+	}
+
 	r = rfbi_runtime_get();
 	if (r)
 		return r;

drivers/video/omap2/dss/sdi.c

@@ -55,6 +55,11 @@ int omapdss_sdi_display_enable(struct omap_dss_device *dssdev)
 	unsigned long pck;
 	int r;
 
+	if (dssdev->manager == NULL) {
+		DSSERR("failed to enable display: no manager\n");
+		return -ENODEV;
+	}
+
 	r = omap_dss_start_device(dssdev);
 	if (r) {
 		DSSERR("failed to start device\n");