igb: A fix to VF TX rate limit

There is a need to configure MMW_SIZE in register RTTBCNRM with a correct
value. For 82576 device, the value should be 0x14.

Signed-off-by: Lior Levy <lior.levy@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/e1000_regs.h

@@ -117,6 +117,7 @@
 
 /* TX Rate Limit Registers */
 #define E1000_RTTDQSEL	0x3604	/* Tx Desc Plane Queue Select - WO */
+#define E1000_RTTBCNRM	0x3690	/* Tx BCN Rate-scheduler MMW */
 #define E1000_RTTBCNRC	0x36B0	/* Tx BCN Rate-Scheduler Config - WO */
 
 /* Split and Replication RX Control - RW */

drivers/net/ethernet/intel/igb/igb_main.c

@@ -6997,6 +6997,11 @@ static void igb_set_vf_rate_limit(struct e1000_hw *hw, int vf, int tx_rate,
 	}
 
 	wr32(E1000_RTTDQSEL, vf); /* vf X uses queue X */
+	/*
+	 * Set global transmit compensation time to the MMW_SIZE in RTTBCNRM
+	 * register. MMW_SIZE=0x014 if 9728-byte jumbo is supported.
+	 */
+	wr32(E1000_RTTBCNRM, 0x14);
 	wr32(E1000_RTTBCNRC, bcnrc_val);
 }