rt2x00: Disable link tuning in rt2500usb

In the legacy rt2570 driver the link tuner was never
really called. And now the reason has finally become
apparent: It breaks TX capabilities

As soon as the device has been associated all following
TX frames will be queued in the hardware and never transmitted
to the air. Disabling sections of the link tuner did not
have the expected result, but completely disabling the
link tuner did have the right result (Both of my rt2570 devices
came back to life).

This should fix Fedora bug: 411481

v2: Fix typos
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2500usb.c

@@ -633,6 +633,16 @@ static void rt2500usb_reset_tuner(struct rt2x00_dev *rt2x00dev)
 	rt2x00dev->link.vgc_level = value;
 }
 
+/*
+ * NOTE: This function is directly ported from legacy driver, but
+ * despite it being declared it was never called. Although link tuning
+ * sounds like a good idea, and usually works well for the other drivers,
+ * it does _not_ work with rt2500usb. Enabling this function will result
+ * in TX capabilities only until association kicks in. Immediately
+ * after the successful association all TX frames will be kept in the
+ * hardware queue and never transmitted.
+ */
+#if 0
 static void rt2500usb_link_tuner(struct rt2x00_dev *rt2x00dev)
 {
 	int rssi = rt2x00_get_link_rssi(&rt2x00dev->link);
@@ -752,6 +762,9 @@ static void rt2500usb_link_tuner(struct rt2x00_dev *rt2x00dev)
 		rt2x00dev->link.vgc_level = r17;
 	}
 }
+#else
+#define rt2500usb_link_tuner	NULL
+#endif
 
 /*
  * Initialization functions.
@@ -1737,6 +1750,7 @@ static int rt2500usb_probe_hw(struct rt2x00_dev *rt2x00dev)
 	__set_bit(DRIVER_REQUIRE_ATIM_QUEUE, &rt2x00dev->flags);
 	__set_bit(DRIVER_REQUIRE_BEACON_GUARD, &rt2x00dev->flags);
 	__set_bit(DRIVER_REQUIRE_SCHEDULED, &rt2x00dev->flags);
+	__set_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags);
 
 	/*
 	 * Set the rssi offset.