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>
diff --git a/drivers/net/ixgbe/ixgbe_dcb.c b/drivers/net/ixgbe/ixgbe_dcb.c
index 8bb9ddb..0d44c64 100644
--- a/drivers/net/ixgbe/ixgbe_dcb.c
+++ b/drivers/net/ixgbe/ixgbe_dcb.c
@@ -43,9 +43,12 @@
* ixgbe_dcb_check_config().
*/
s32 ixgbe_dcb_calculate_tc_credits(struct ixgbe_dcb_config *dcb_config,
- u8 direction)
+ int max_frame, u8 direction)
{
struct tc_bw_alloc *p;
+ int min_credit;
+ int min_multiplier;
+ int min_percent = 100;
s32 ret_val = 0;
/* Initialization values default for Tx settings */
u32 credit_refill = 0;
@@ -59,6 +62,31 @@
goto out;
}
+ min_credit = ((max_frame / 2) + DCB_CREDIT_QUANTUM - 1) /
+ DCB_CREDIT_QUANTUM;
+
+ /* Find smallest link percentage */
+ for (i = 0; i < MAX_TRAFFIC_CLASS; i++) {
+ p = &dcb_config->tc_config[i].path[direction];
+ bw_percent = dcb_config->bw_percentage[direction][p->bwg_id];
+ link_percentage = p->bwg_percent;
+
+ link_percentage = (link_percentage * bw_percent) / 100;
+
+ if (link_percentage && link_percentage < min_percent)
+ min_percent = link_percentage;
+ }
+
+ /*
+ * The ratio between traffic classes will control the bandwidth
+ * percentages seen on the wire. To calculate this ratio we use
+ * a multiplier. It is required that the refill credits must be
+ * larger than the max frame size so here we find the smallest
+ * multiplier that will allow all bandwidth percentages to be
+ * greater than the max frame size.
+ */
+ min_multiplier = (min_credit / min_percent) + 1;
+
/* Find out the link percentage for each TC first */
for (i = 0; i < MAX_TRAFFIC_CLASS; i++) {
p = &dcb_config->tc_config[i].path[direction];
@@ -73,8 +101,9 @@
/* Save link_percentage for reference */
p->link_percent = (u8)link_percentage;
- /* Calculate credit refill and save it */
- credit_refill = link_percentage * MINIMUM_CREDIT_REFILL;
+ /* Calculate credit refill ratio using multiplier */
+ credit_refill = min(link_percentage * min_multiplier,
+ MAX_CREDIT_REFILL);
p->data_credits_refill = (u16)credit_refill;
/* Calculate maximum credit for the TC */
@@ -85,8 +114,8 @@
* of a TC is too small, the maximum credit may not be
* enough to send out a jumbo frame in data plane arbitration.
*/
- if (credit_max && (credit_max < MINIMUM_CREDIT_FOR_JUMBO))
- credit_max = MINIMUM_CREDIT_FOR_JUMBO;
+ if (credit_max && (credit_max < min_credit))
+ credit_max = min_credit;
if (direction == DCB_TX_CONFIG) {
/*