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

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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>
This commit is contained in:
John Fastabend
2010-10-28 00:59:57 +00:00
committed by David S. Miller
parent affa9dfb04
commit 9806307a1c
5 changed files with 54 additions and 10 deletions
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39
drivers/net/ixgbe/ixgbe_dcb.c
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@@ -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 @@ s32 ixgbe_dcb_calculate_tc_credits(struct ixgbe_dcb_config *dcb_config,
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 @@ s32 ixgbe_dcb_calculate_tc_credits(struct ixgbe_dcb_config *dcb_config,
/* 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 @@ s32 ixgbe_dcb_calculate_tc_credits(struct ixgbe_dcb_config *dcb_config,
* 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) {
/*