From 9806307a1c5a2a79e268ae4e78b437d38c8adf7f Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Thu, 28 Oct 2010 00:59:57 +0000 Subject: 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 Tested-by: Ross Brattain Signed-off-by: Jeff Kirsher Signed-off-by: David S. Miller --- drivers/net/ixgbe/ixgbe_dcb.c | 39 ++++++++++++++++++++++++++++++++++----- 1 file changed, 34 insertions(+), 5 deletions(-) (limited to 'drivers/net/ixgbe/ixgbe_dcb.c') diff --git a/drivers/net/ixgbe/ixgbe_dcb.c b/drivers/net/ixgbe/ixgbe_dcb.c index 8bb9ddb6dff..0d44c6470ca 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 @@ 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) { /* -- cgit v1.2.3-70-g09d2