rt2x00: Place mutex around USB register access

[powerpc.git] / drivers / net / wireless / rt2x00 / rt2x00.h

diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index 2cd2c9f..75c9a76 100644 (file)
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -31,6 +31,7 @@
 #include <linux/skbuff.h>
 #include <linux/workqueue.h>
 #include <linux/firmware.h>
+#include <linux/mutex.h>
 
 #include <net/mac80211.h>
 
@@ -658,6 +659,18 @@ struct rt2x00_dev {
        void __iomem *csr_addr;
        void *csr_cache;
 
+       /*
+        * Mutex to protect register accesses on USB devices.
+        * There are 2 reasons this is needed, one is to ensure
+        * use of the csr_cache (for USB devices) by one thread
+        * isn't corrupted by another thread trying to access it.
+        * The other is that access to BBP and RF registers
+        * require multiple BUS transactions and if another thread
+        * attempted to access one of those registers at the same
+        * time one of the writes could silently fail.
+        */
+       struct mutex usb_cache_mutex;
+
        /*
         * Interface configuration.
         */