plugin-base: fix finding the physical device again

Don't mis-use udev's ID_BUS key.

src/mm-plugin-base.c

@@ -680,48 +680,37 @@ get_driver_name (GUdevDevice *device)
 static GUdevDevice *
 real_find_physical_device (MMPluginBase *plugin, GUdevDevice *child)
 {
-    GUdevDevice *parent = NULL, *physdev = NULL;
+    GUdevDevice *iter, *old = NULL;
+    GUdevDevice *physdev = NULL;
     const char *subsys, *type;
+    guint32 i = 0;
+    gboolean is_usb = FALSE, is_pci = FALSE;
 
     g_return_val_if_fail (child != NULL, NULL);
 
-    subsys = g_udev_device_get_subsystem (child);
-    g_assert (subsys);
-    if (strcmp (subsys, "usb") && strcmp (subsys, "pci")) {
-        /* Try the parent */
-        parent = g_udev_device_get_parent (child);
-        if (!parent)
-            goto out;
-
-        subsys = g_udev_device_get_subsystem (parent);
-        if (strcmp (subsys, "usb") && strcmp (subsys, "pci"))
-            goto out;
-    }
-
-    if (!strcmp (subsys, "usb")) {
-        GUdevDevice *iter, *old = NULL;
-
-        /* Walk the parents to find the 'usb_device' for this device. */
     iter = g_object_ref (child);
-        while (iter) {
+    while (iter && i++ < 5) {
+        subsys = g_udev_device_get_subsystem (iter);
+        if (subsys) {
+            if (is_usb || !strcmp (subsys, "usb")) {
+                is_usb = TRUE;
                 type = g_udev_device_get_devtype (iter);
                 if (type && !strcmp (type, "usb_device")) {
                     physdev = iter;
                     break;
                 }
+            } else if (is_pci || !strcmp (subsys, "pci")) {
+                is_pci = TRUE;
+                physdev = iter;
+                break;
+            }
+        }
 
         old = iter;
         iter = g_udev_device_get_parent (old);
         g_object_unref (old);
     }
-    } else if (!strcmp (subsys, "pci"))
-        physdev = g_udev_device_get_parent (child);
 
-    // FIXME: pcmcia (like Sierra 850/860)
-
-out:
-    if (parent)
-        g_object_unref (parent);
     return physdev;
 }
 

src/mm-plugin-base.h

@@ -102,6 +102,10 @@ struct _MMPluginBaseClass {
     void (*cancel_task)       (MMPluginBase *plugin,
                                MMPluginBaseSupportsTask *task);
 
+    /* Find a the physical device of a port, ie the USB or PCI or whatever
+     * "master" device that owns the port.  The GUdevDevice object returned
+     * will be unref-ed by the caller.
+     */
     GUdevDevice * (*find_physical_device) (MMPluginBase *plugin,
                                            GUdevDevice *port);