libertas: cope with both old and new mesh TLV values

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/libertas/main.c b/drivers/net/wireless/libertas/main.c
index 5e2f329..2409df8 100644
--- a/drivers/net/wireless/libertas/main.c
+++ b/drivers/net/wireless/libertas/main.c
@@ -1171,8 +1171,33 @@
 	}
 	if (device_create_file(&dev->dev, &dev_attr_lbs_rtap))
 		lbs_pr_err("cannot register lbs_rtap attribute\n");
-	if (device_create_file(&dev->dev, &dev_attr_lbs_mesh))
-		lbs_pr_err("cannot register lbs_mesh attribute\n");
+
+	/* Enable mesh, if supported, and work out which TLV it uses.
+	   0x100 + 291 is an unofficial value used in 5.110.20.pXX
+	   0x100 + 37 is the official value used in 5.110.21.pXX
+	   but we check them in that order because 20.pXX doesn't 
+	   give an error -- it just silently fails. */
+
+	/* 5.110.20.pXX firmware will fail the command if the channel
+	   doesn't match the existing channel. But only if the TLV
+	   is correct. If the channel is wrong, _BOTH_ versions will
+	   give an error to 0x100+291, and allow 0x100+37 to succeed.
+	   It's just that 5.110.20.pXX will not have done anything
+	   useful */
+
+	lbs_update_channel(priv);
+	priv->mesh_tlv = 0x100 + 291;
+	if (lbs_mesh_config(priv, 1)) {
+		priv->mesh_tlv = 0x100 + 37;
+		if (lbs_mesh_config(priv, 1))
+			priv->mesh_tlv = 0;
+	}
+	if (priv->mesh_tlv) {
+		lbs_add_mesh(priv);
+
+		if (device_create_file(&dev->dev, &dev_attr_lbs_mesh))
+			lbs_pr_err("cannot register lbs_mesh attribute\n");
+	}
 
 	lbs_debugfs_init_one(priv, dev);
 
@@ -1201,7 +1226,8 @@
 
 	lbs_debugfs_remove_one(priv);
 	device_remove_file(&dev->dev, &dev_attr_lbs_rtap);
-	device_remove_file(&dev->dev, &dev_attr_lbs_mesh);
+	if (priv->mesh_tlv)
+		device_remove_file(&dev->dev, &dev_attr_lbs_mesh);
 
 	/* Flush pending command nodes */
 	spin_lock_irqsave(&priv->driver_lock, flags);