OMAPDSS: add module_get/put to omap_dss_get/put_device()

omap_dss_get_device() should be called for omap_dss_device before it is
used to increase its refcount. Currently we only increase the refcount
for the underlying device.

This patch adds managing the ref count to the underlying module also,
which contains the ops for the omap_dss_device.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/display.c

@@ -158,15 +158,24 @@ void omapdss_unregister_display(struct omap_dss_device *dssdev)
 }
 EXPORT_SYMBOL(omapdss_unregister_display);
 
-void omap_dss_get_device(struct omap_dss_device *dssdev)
+struct omap_dss_device *omap_dss_get_device(struct omap_dss_device *dssdev)
 {
-	get_device(dssdev->dev);
+	if (!try_module_get(dssdev->owner))
+		return NULL;
+
+	if (get_device(dssdev->dev) == NULL) {
+		module_put(dssdev->owner);
+		return NULL;
+	}
+
+	return dssdev;
 }
 EXPORT_SYMBOL(omap_dss_get_device);
 
 void omap_dss_put_device(struct omap_dss_device *dssdev)
 {
 	put_device(dssdev->dev);
+	module_put(dssdev->owner);
 }
 EXPORT_SYMBOL(omap_dss_put_device);
 

include/video/omapdss.h

@@ -767,7 +767,7 @@ void omap_dss_unregister_driver(struct omap_dss_driver *);
 int omapdss_register_display(struct omap_dss_device *dssdev);
 void omapdss_unregister_display(struct omap_dss_device *dssdev);
 
-void omap_dss_get_device(struct omap_dss_device *dssdev);
+struct omap_dss_device *omap_dss_get_device(struct omap_dss_device *dssdev);
 void omap_dss_put_device(struct omap_dss_device *dssdev);
 #define for_each_dss_dev(d) while ((d = omap_dss_get_next_device(d)) != NULL)
 struct omap_dss_device *omap_dss_get_next_device(struct omap_dss_device *from);