1 files changed, 18 insertions, 2 deletions

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index 4eef798fbb7b..6af8ebcf35f0 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -6690,13 +6690,29 @@ static void tg3_timer(unsigned long __opaque)
                 tp->timer_counter = tp->timer_multiplier;
         }
 
-        /* Heartbeat is only sent once every 2 seconds.  */
+        /* Heartbeat is only sent once every 2 seconds.
+         *
+         * The heartbeat is to tell the ASF firmware that the host
+         * driver is still alive.  In the event that the OS crashes,
+         * ASF needs to reset the hardware to free up the FIFO space
+         * that may be filled with rx packets destined for the host.
+         * If the FIFO is full, ASF will no longer function properly.
+         *
+         * Unintended resets have been reported on real time kernels
+         * where the timer doesn't run on time.  Netpoll will also have
+         * same problem.
+         *
+         * The new FWCMD_NICDRV_ALIVE3 command tells the ASF firmware
+         * to check the ring condition when the heartbeat is expiring
+         * before doing the reset.  This will prevent most unintended
+         * resets.
+         */
         if (!--tp->asf_counter) {
                 if (tp->tg3_flags & TG3_FLAG_ENABLE_ASF) {
                         u32 val;
 
                         tg3_write_mem(tp, NIC_SRAM_FW_CMD_MBOX,
-                                      FWCMD_NICDRV_ALIVE2);
+                                      FWCMD_NICDRV_ALIVE3);
                         tg3_write_mem(tp, NIC_SRAM_FW_CMD_LEN_MBOX, 4);
                         /* 5 seconds timeout */
                         tg3_write_mem(tp, NIC_SRAM_FW_CMD_DATA_MBOX, 5);