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Commit 9806307a authored by John Fastabend's avatar John Fastabend Committed by David S. Miller
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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: default avatarJohn Fastabend <john.r.fastabend@intel.com>
Tested-by: default avatarRoss Brattain <ross.b.brattain@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent affa9dfb

drivers/net/ixgbe/ixgbe_dcb.c

+34 −5
Original line number Diff line number Diff line
@@ -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) {

			/*

drivers/net/ixgbe/ixgbe_dcb.h

+2 −3
Original line number Diff line number Diff line
@@ -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 */

drivers/net/ixgbe/ixgbe_dcb_82599.c

+5 −0
Original line number Diff line number Diff line
@@ -397,6 +397,11 @@ static s32 ixgbe_dcb_config_82599(struct ixgbe_hw *hw) 
	reg &= ~IXGBE_RTTDCS_ARBDIS;

	IXGBE_WRITE_REG(hw, IXGBE_RTTDCS, reg);



	/* Enable Security TX Buffer IFG for DCB */

	reg = IXGBE_READ_REG(hw, IXGBE_SECTXMINIFG);

	reg |= IXGBE_SECTX_DCB;

	IXGBE_WRITE_REG(hw, IXGBE_SECTXMINIFG, reg);



	return 0;

}

drivers/net/ixgbe/ixgbe_dcb_82599.h

+3 −0
Original line number Diff line number Diff line
@@ -95,6 +95,9 @@ 


#define IXGBE_TXPBTHRESH_DCB    0xA        /* THRESH value for DCB mode */



/* SECTXMINIFG DCB */

#define IXGBE_SECTX_DCB		0x00001F00 /* DCB TX Buffer IFG */





/* DCB hardware-specific driver APIs */

drivers/net/ixgbe/ixgbe_main.c

+10 −2
Original line number Diff line number Diff line
@@ -3347,6 +3347,7 @@ static void ixgbe_napi_disable_all(struct ixgbe_adapter *adapter) 
static void ixgbe_configure_dcb(struct ixgbe_adapter *adapter)

{

	struct ixgbe_hw *hw = &adapter->hw;

	int max_frame = adapter->netdev->mtu + ETH_HLEN + ETH_FCS_LEN;

	u32 txdctl;

	int i, j;
@@ -3359,8 +3360,15 @@ static void ixgbe_configure_dcb(struct ixgbe_adapter *adapter) 
	if (hw->mac.type == ixgbe_mac_82598EB)

		netif_set_gso_max_size(adapter->netdev, 32768);



	ixgbe_dcb_calculate_tc_credits(&adapter->dcb_cfg, DCB_TX_CONFIG);

	ixgbe_dcb_calculate_tc_credits(&adapter->dcb_cfg, DCB_RX_CONFIG);

#ifdef CONFIG_FCOE

	if (adapter->netdev->features & NETIF_F_FCOE_MTU)

		max_frame = max(max_frame, IXGBE_FCOE_JUMBO_FRAME_SIZE);

#endif



	ixgbe_dcb_calculate_tc_credits(&adapter->dcb_cfg, max_frame,

					DCB_TX_CONFIG);

	ixgbe_dcb_calculate_tc_credits(&adapter->dcb_cfg, max_frame,

					DCB_RX_CONFIG);



	/* reconfigure the hardware */

	ixgbe_dcb_hw_config(&adapter->hw, &adapter->dcb_cfg);