ixgbe: DCB, fix TX hang occurring in stress condition with PFC

The DCB credits refill quantum _must_ be greater than half the max
packet size. This is needed to guarantee that TX DMA operations
are not attempted during a pause state. Additionally, the min IFG
must be set correctly for DCB mode. If a DMA operation is
requested unexpectedly during the pause state the HW data
store may be corrupted leading to a DMA hang.  The DMA hang
requires a reset to correct. This fixes the HW configuration
to avoid this condition.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 3 deletions

diff --git a/drivers/net/ixgbe/ixgbe_dcb.h b/drivers/net/ixgbe/ixgbe_dcb.h
index eb1059f09da0..0208a87b129e 100644
--- a/drivers/net/ixgbe/ixgbe_dcb.h
+++ b/drivers/net/ixgbe/ixgbe_dcb.h
@@ -150,15 +150,14 @@ struct ixgbe_dcb_config {
 /* DCB driver APIs */
 
 /* DCB credits calculation */
-s32 ixgbe_dcb_calculate_tc_credits(struct ixgbe_dcb_config *, u8);
+s32 ixgbe_dcb_calculate_tc_credits(struct ixgbe_dcb_config *, int, u8);
 
 /* DCB hw initialization */
 s32 ixgbe_dcb_hw_config(struct ixgbe_hw *, struct ixgbe_dcb_config *);
 
 /* DCB definitions for credit calculation */
+#define DCB_CREDIT_QUANTUM      64   /* DCB Quantum */
 #define MAX_CREDIT_REFILL       511  /* 0x1FF * 64B = 32704B */
-#define MINIMUM_CREDIT_REFILL   5    /* 5*64B = 320B */
-#define MINIMUM_CREDIT_FOR_JUMBO 145  /* 145= UpperBound((9*1024+54)/64B) for 9KB jumbo frame */
 #define DCB_MAX_TSO_SIZE        (32*1024) /* MAX TSO packet size supported in DCB mode */
 #define MINIMUM_CREDIT_FOR_TSO  (DCB_MAX_TSO_SIZE/64 + 1) /* 513 for 32KB TSO packet */
 #define MAX_CREDIT              4095 /* Maximum credit supported: 256KB * 1204 / 64B */