linux-vybrid_public/drivers/net/sfc/falcon_xmac.c

/****************************************************************************
 * Driver for Solarflare Solarstorm network controllers and boards
 * Copyright 2005-2006 Fen Systems Ltd.
 * Copyright 2006-2008 Solarflare Communications Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation, incorporated herein by reference.
 */

#include <linux/delay.h>
#include "net_driver.h"
#include "efx.h"
#include "falcon.h"
#include "falcon_hwdefs.h"
#include "falcon_io.h"
#include "mac.h"
#include "gmii.h"
#include "mdio_10g.h"
#include "phy.h"
#include "boards.h"
#include "workarounds.h"

/**************************************************************************
 *
 * MAC register access
 *
 **************************************************************************/

/* Offset of an XMAC register within Falcon */
#define FALCON_XMAC_REG(mac_reg)					\
	(FALCON_XMAC_REGBANK + ((mac_reg) * FALCON_XMAC_REG_SIZE))

void falcon_xmac_writel(struct efx_nic *efx,
			 efx_dword_t *value, unsigned int mac_reg)
{
	efx_oword_t temp;

	EFX_POPULATE_OWORD_1(temp, MAC_DATA, EFX_DWORD_FIELD(*value, MAC_DATA));
	falcon_write(efx, &temp, FALCON_XMAC_REG(mac_reg));
}

void falcon_xmac_readl(struct efx_nic *efx,
		       efx_dword_t *value, unsigned int mac_reg)
{
	efx_oword_t temp;

	falcon_read(efx, &temp, FALCON_XMAC_REG(mac_reg));
	EFX_POPULATE_DWORD_1(*value, MAC_DATA, EFX_OWORD_FIELD(temp, MAC_DATA));
}

/**************************************************************************
 *
 * MAC operations
 *
 *************************************************************************/
static int falcon_reset_xmac(struct efx_nic *efx)
{
	efx_dword_t reg;
	int count;

	EFX_POPULATE_DWORD_1(reg, XM_CORE_RST, 1);
	falcon_xmac_writel(efx, &reg, XM_GLB_CFG_REG_MAC);

	for (count = 0; count < 10000; count++) {	/* wait upto 100ms */
		falcon_xmac_readl(efx, &reg, XM_GLB_CFG_REG_MAC);
		if (EFX_DWORD_FIELD(reg, XM_CORE_RST) == 0)
			return 0;
		udelay(10);
	}

	/* This often fails when DSP is disabled, ignore it */
	if (sfe4001_phy_flash_cfg != 0)
		return 0;

	EFX_ERR(efx, "timed out waiting for XMAC core reset\n");
	return -ETIMEDOUT;
}

/* Configure the XAUI driver that is an output from Falcon */
static void falcon_setup_xaui(struct efx_nic *efx)
{
	efx_dword_t sdctl, txdrv;

	/* Move the XAUI into low power, unless there is no PHY, in
	 * which case the XAUI will have to drive a cable. */
	if (efx->phy_type == PHY_TYPE_NONE)
		return;

	falcon_xmac_readl(efx, &sdctl, XX_SD_CTL_REG_MAC);
	EFX_SET_DWORD_FIELD(sdctl, XX_HIDRVD, XX_SD_CTL_DRV_DEFAULT);
	EFX_SET_DWORD_FIELD(sdctl, XX_LODRVD, XX_SD_CTL_DRV_DEFAULT);
	EFX_SET_DWORD_FIELD(sdctl, XX_HIDRVC, XX_SD_CTL_DRV_DEFAULT);
	EFX_SET_DWORD_FIELD(sdctl, XX_LODRVC, XX_SD_CTL_DRV_DEFAULT);
	EFX_SET_DWORD_FIELD(sdctl, XX_HIDRVB, XX_SD_CTL_DRV_DEFAULT);
	EFX_SET_DWORD_FIELD(sdctl, XX_LODRVB, XX_SD_CTL_DRV_DEFAULT);
	EFX_SET_DWORD_FIELD(sdctl, XX_HIDRVA, XX_SD_CTL_DRV_DEFAULT);
	EFX_SET_DWORD_FIELD(sdctl, XX_LODRVA, XX_SD_CTL_DRV_DEFAULT);
	falcon_xmac_writel(efx, &sdctl, XX_SD_CTL_REG_MAC);

	EFX_POPULATE_DWORD_8(txdrv,
			     XX_DEQD, XX_TXDRV_DEQ_DEFAULT,
			     XX_DEQC, XX_TXDRV_DEQ_DEFAULT,
			     XX_DEQB, XX_TXDRV_DEQ_DEFAULT,
			     XX_DEQA, XX_TXDRV_DEQ_DEFAULT,
			     XX_DTXD, XX_TXDRV_DTX_DEFAULT,
			     XX_DTXC, XX_TXDRV_DTX_DEFAULT,
			     XX_DTXB, XX_TXDRV_DTX_DEFAULT,
			     XX_DTXA, XX_TXDRV_DTX_DEFAULT);
	falcon_xmac_writel(efx, &txdrv, XX_TXDRV_CTL_REG_MAC);
}

static void falcon_hold_xaui_in_rst(struct efx_nic *efx)
{
	efx_dword_t reg;

	EFX_ZERO_DWORD(reg);
	EFX_SET_DWORD_FIELD(reg, XX_PWRDNA_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_PWRDNB_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_PWRDNC_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_PWRDND_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_RSTPLLAB_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_RSTPLLCD_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_RESETA_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_RESETB_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_RESETC_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_RESETD_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_RSTXGXSRX_EN, 1);
	EFX_SET_DWORD_FIELD(reg, XX_RSTXGXSTX_EN, 1);
	falcon_xmac_writel(efx, &reg, XX_PWR_RST_REG_MAC);
	udelay(10);
}

static int _falcon_reset_xaui_a(struct efx_nic *efx)
{
	efx_dword_t reg;

	falcon_hold_xaui_in_rst(efx);
	falcon_xmac_readl(efx, &reg, XX_PWR_RST_REG_MAC);

	/* Follow the RAMBUS XAUI data reset sequencing
	 * Channels A and B first: power down, reset PLL, reset, clear
	 */
	EFX_SET_DWORD_FIELD(reg, XX_PWRDNA_EN, 0);
	EFX_SET_DWORD_FIELD(reg, XX_PWRDNB_EN, 0);
	falcon_xmac_writel(efx, &reg, XX_PWR_RST_REG_MAC);
	udelay(10);

	EFX_SET_DWORD_FIELD(reg, XX_RSTPLLAB_EN, 0);
	falcon_xmac_writel(efx, &reg, XX_PWR_RST_REG_MAC);
	udelay(10);

	EFX_SET_DWORD_FIELD(reg, XX_RESETA_EN, 0);
	EFX_SET_DWORD_FIELD(reg, XX_RESETB_EN, 0);
	falcon_xmac_writel(efx, &reg, XX_PWR_RST_REG_MAC);
	udelay(10);

	/* Channels C and D: power down, reset PLL, reset, clear */
	EFX_SET_DWORD_FIELD(reg, XX_PWRDNC_EN, 0);
	EFX_SET_DWORD_FIELD(reg, XX_PWRDND_EN, 0);
	falcon_xmac_writel(efx, &reg, XX_PWR_RST_REG_MAC);
	udelay(10);

	EFX_SET_DWORD_FIELD(reg, XX_RSTPLLCD_EN, 0);
	falcon_xmac_writel(efx, &reg, XX_PWR_RST_REG_MAC);
	udelay(10);

	EFX_SET_DWORD_FIELD(reg, XX_RESETC_EN, 0);
	EFX_SET_DWORD_FIELD(reg, XX_RESETD_EN, 0);
	falcon_xmac_writel(efx, &reg, XX_PWR_RST_REG_MAC);
	udelay(10);

	/* Setup XAUI */
	falcon_setup_xaui(efx);
	udelay(10);

	/* Take XGXS out of reset */
	EFX_ZERO_DWORD(reg);
	falcon_xmac_writel(efx, &reg, XX_PWR_RST_REG_MAC);
	udelay(10);

	return 0;
}

static int _falcon_reset_xaui_b(struct efx_nic *efx)
{
	efx_dword_t reg;
	int count;

	EFX_POPULATE_DWORD_1(reg, XX_RST_XX_EN, 1);
	falcon_xmac_writel(efx, &reg, XX_PWR_RST_REG_MAC);

	/* Give some time for the link to establish */
	for (count = 0; count < 1000; count++) { /* wait upto 10ms */
		falcon_xmac_readl(efx, &reg, XX_PWR_RST_REG_MAC);
		if (EFX_DWORD_FIELD(reg, XX_RST_XX_EN) == 0) {
			falcon_setup_xaui(efx);
			return 0;
		}
		udelay(10);
	}
	EFX_ERR(efx, "timed out waiting for XAUI/XGXS reset\n");
	return -ETIMEDOUT;
}

int falcon_reset_xaui(struct efx_nic *efx)
{
	int rc;

	if (EFX_WORKAROUND_9388(efx)) {
		falcon_hold_xaui_in_rst(efx);
		efx->phy_op->reset_xaui(efx);
		rc = _falcon_reset_xaui_a(efx);
	} else {
		rc = _falcon_reset_xaui_b(efx);
	}
	return rc;
}

static int falcon_xgmii_status(struct efx_nic *efx)
{
	efx_dword_t reg;

	if (FALCON_REV(efx) < FALCON_REV_B0)
		return 1;

	/* The ISR latches, so clear it and re-read */
	falcon_xmac_readl(efx, &reg, XM_MGT_INT_REG_MAC_B0);
	falcon_xmac_readl(efx, &reg, XM_MGT_INT_REG_MAC_B0);

	if (EFX_DWORD_FIELD(reg, XM_LCLFLT) ||
	    EFX_DWORD_FIELD(reg, XM_RMTFLT)) {
		EFX_INFO(efx, "MGT_INT: "EFX_DWORD_FMT"\n", EFX_DWORD_VAL(reg));
		return 0;
	}

	return 1;
}

static void falcon_mask_status_intr(struct efx_nic *efx, int enable)
{
	efx_dword_t reg;

	if (FALCON_REV(efx) < FALCON_REV_B0)
		return;

	/* Flush the ISR */
	if (enable)
		falcon_xmac_readl(efx, &reg, XM_MGT_INT_REG_MAC_B0);

	EFX_POPULATE_DWORD_2(reg,
			     XM_MSK_RMTFLT, !enable,
			     XM_MSK_LCLFLT, !enable);
	falcon_xmac_writel(efx, &reg, XM_MGT_INT_MSK_REG_MAC_B0);
}

int falcon_init_xmac(struct efx_nic *efx)
{
	int rc;

	/* Initialize the PHY first so the clock is around */
	rc = efx->phy_op->init(efx);
	if (rc)
		goto fail1;

	rc = falcon_reset_xaui(efx);
	if (rc)
		goto fail2;

	/* Wait again. Give the PHY and MAC time to come back */
	schedule_timeout_uninterruptible(HZ / 10);

	rc = falcon_reset_xmac(efx);
	if (rc)
		goto fail2;

	falcon_mask_status_intr(efx, 1);
	return 0;

 fail2:
	efx->phy_op->fini(efx);
 fail1:
	return rc;
}

int falcon_xaui_link_ok(struct efx_nic *efx)
{
	efx_dword_t reg;
	int align_done, sync_status, link_ok = 0;

	/* Read link status */
	falcon_xmac_readl(efx, &reg, XX_CORE_STAT_REG_MAC);

	align_done = EFX_DWORD_FIELD(reg, XX_ALIGN_DONE);
	sync_status = EFX_DWORD_FIELD(reg, XX_SYNC_STAT);
	if (align_done && (sync_status == XX_SYNC_STAT_DECODE_SYNCED))
		link_ok = 1;

	/* Clear link status ready for next read */
	EFX_SET_DWORD_FIELD(reg, XX_COMMA_DET, XX_COMMA_DET_RESET);
	EFX_SET_DWORD_FIELD(reg, XX_CHARERR, XX_CHARERR_RESET);
	EFX_SET_DWORD_FIELD(reg, XX_DISPERR, XX_DISPERR_RESET);
	falcon_xmac_writel(efx, &reg, XX_CORE_STAT_REG_MAC);

	/* If the link is up, then check the phy side of the xaui link
	 * (error conditions from the wire side propoagate back through
	 * the phy to the xaui side). */
	if (efx->link_up && link_ok) {
		int has_phyxs = efx->phy_op->mmds & (1 << MDIO_MMD_PHYXS);
		if (has_phyxs)
			link_ok = mdio_clause45_phyxgxs_lane_sync(efx);
	}

	/* If the PHY and XAUI links are up, then check the mac's xgmii
	 * fault state */
	if (efx->link_up && link_ok)
		link_ok = falcon_xgmii_status(efx);

	return link_ok;
}

static void falcon_reconfigure_xmac_core(struct efx_nic *efx)
{
	unsigned int max_frame_len;
	efx_dword_t reg;
	int rx_fc = (efx->flow_control & EFX_FC_RX) ? 1 : 0;

	/* Configure MAC  - cut-thru mode is hard wired on */
	EFX_POPULATE_DWORD_3(reg,
			     XM_RX_JUMBO_MODE, 1,
			     XM_TX_STAT_EN, 1,
			     XM_RX_STAT_EN, 1);
	falcon_xmac_writel(efx, &reg, XM_GLB_CFG_REG_MAC);

	/* Configure TX */
	EFX_POPULATE_DWORD_6(reg,
			     XM_TXEN, 1,
			     XM_TX_PRMBL, 1,
			     XM_AUTO_PAD, 1,
			     XM_TXCRC, 1,
			     XM_FCNTL, 1,
			     XM_IPG, 0x3);
	falcon_xmac_writel(efx, &reg, XM_TX_CFG_REG_MAC);

	/* Configure RX */
	EFX_POPULATE_DWORD_5(reg,
			     XM_RXEN, 1,
			     XM_AUTO_DEPAD, 0,
			     XM_ACPT_ALL_MCAST, 1,
			     XM_ACPT_ALL_UCAST, efx->promiscuous,
			     XM_PASS_CRC_ERR, 1);
	falcon_xmac_writel(efx, &reg, XM_RX_CFG_REG_MAC);

	/* Set frame length */
	max_frame_len = EFX_MAX_FRAME_LEN(efx->net_dev->mtu);
	EFX_POPULATE_DWORD_1(reg, XM_MAX_RX_FRM_SIZE, max_frame_len);
	falcon_xmac_writel(efx, &reg, XM_RX_PARAM_REG_MAC);
	EFX_POPULATE_DWORD_2(reg,
			     XM_MAX_TX_FRM_SIZE, max_frame_len,
			     XM_TX_JUMBO_MODE, 1);
	falcon_xmac_writel(efx, &reg, XM_TX_PARAM_REG_MAC);

	EFX_POPULATE_DWORD_2(reg,
			     XM_PAUSE_TIME, 0xfffe, /* MAX PAUSE TIME */
			     XM_DIS_FCNTL, rx_fc ? 0 : 1);
	falcon_xmac_writel(efx, &reg, XM_FC_REG_MAC);

	/* Set MAC address */
	EFX_POPULATE_DWORD_4(reg,
			     XM_ADR_0, efx->net_dev->dev_addr[0],
			     XM_ADR_1, efx->net_dev->dev_addr[1],
			     XM_ADR_2, efx->net_dev->dev_addr[2],
			     XM_ADR_3, efx->net_dev->dev_addr[3]);
	falcon_xmac_writel(efx, &reg, XM_ADR_LO_REG_MAC);
	EFX_POPULATE_DWORD_2(reg,
			     XM_ADR_4, efx->net_dev->dev_addr[4],
			     XM_ADR_5, efx->net_dev->dev_addr[5]);
	falcon_xmac_writel(efx, &reg, XM_ADR_HI_REG_MAC);
}

/* Try and bring the Falcon side of the Falcon-Phy XAUI link fails
 * to come back up. Bash it until it comes back up */
static int falcon_check_xaui_link_up(struct efx_nic *efx)
{
	int max_tries, tries;
	tries = EFX_WORKAROUND_5147(efx) ? 5 : 1;
	max_tries = tries;

	if (efx->phy_type == PHY_TYPE_NONE)
		return 0;

	while (tries) {
		if (falcon_xaui_link_ok(efx))
			return 1;

		EFX_LOG(efx, "%s Clobbering XAUI (%d tries left).\n",
			__func__, tries);
		(void) falcon_reset_xaui(efx);
		udelay(200);
		tries--;
	}

	EFX_ERR(efx, "Failed to bring XAUI link back up in %d tries!\n",
		max_tries);
	return 0;
}

void falcon_reconfigure_xmac(struct efx_nic *efx)
{
	int xaui_link_ok;

	falcon_mask_status_intr(efx, 0);

	falcon_deconfigure_mac_wrapper(efx);
	efx->phy_op->reconfigure(efx);
	falcon_reconfigure_xmac_core(efx);
	falcon_reconfigure_mac_wrapper(efx);

	/* Ensure XAUI link is up */
	xaui_link_ok = falcon_check_xaui_link_up(efx);

	if (xaui_link_ok && efx->link_up)
		falcon_mask_status_intr(efx, 1);
}

void falcon_fini_xmac(struct efx_nic *efx)
{
	/* Isolate the MAC - PHY */
	falcon_deconfigure_mac_wrapper(efx);

	/* Potentially power down the PHY */
	efx->phy_op->fini(efx);
}

void falcon_update_stats_xmac(struct efx_nic *efx)
{
	struct efx_mac_stats *mac_stats = &efx->mac_stats;
	int rc;

	rc = falcon_dma_stats(efx, XgDmaDone_offset);
	if (rc)
		return;

	/* Update MAC stats from DMAed values */
	FALCON_STAT(efx, XgRxOctets, rx_bytes);
	FALCON_STAT(efx, XgRxOctetsOK, rx_good_bytes);
	FALCON_STAT(efx, XgRxPkts, rx_packets);
	FALCON_STAT(efx, XgRxPktsOK, rx_good);
	FALCON_STAT(efx, XgRxBroadcastPkts, rx_broadcast);
	FALCON_STAT(efx, XgRxMulticastPkts, rx_multicast);
	FALCON_STAT(efx, XgRxUnicastPkts, rx_unicast);
	FALCON_STAT(efx, XgRxUndersizePkts, rx_lt64);
	FALCON_STAT(efx, XgRxOversizePkts, rx_gtjumbo);
	FALCON_STAT(efx, XgRxJabberPkts, rx_bad_gtjumbo);
	FALCON_STAT(efx, XgRxUndersizeFCSerrorPkts, rx_bad_lt64);
	FALCON_STAT(efx, XgRxDropEvents, rx_overflow);
	FALCON_STAT(efx, XgRxFCSerrorPkts, rx_bad);
	FALCON_STAT(efx, XgRxAlignError, rx_align_error);
	FALCON_STAT(efx, XgRxSymbolError, rx_symbol_error);
	FALCON_STAT(efx, XgRxInternalMACError, rx_internal_error);
	FALCON_STAT(efx, XgRxControlPkts, rx_control);
	FALCON_STAT(efx, XgRxPausePkts, rx_pause);
	FALCON_STAT(efx, XgRxPkts64Octets, rx_64);
	FALCON_STAT(efx, XgRxPkts65to127Octets, rx_65_to_127);
	FALCON_STAT(efx, XgRxPkts128to255Octets, rx_128_to_255);
	FALCON_STAT(efx, XgRxPkts256to511Octets, rx_256_to_511);
	FALCON_STAT(efx, XgRxPkts512to1023Octets, rx_512_to_1023);
	FALCON_STAT(efx, XgRxPkts1024to15xxOctets, rx_1024_to_15xx);
	FALCON_STAT(efx, XgRxPkts15xxtoMaxOctets, rx_15xx_to_jumbo);
	FALCON_STAT(efx, XgRxLengthError, rx_length_error);
	FALCON_STAT(efx, XgTxPkts, tx_packets);
	FALCON_STAT(efx, XgTxOctets, tx_bytes);
	FALCON_STAT(efx, XgTxMulticastPkts, tx_multicast);
	FALCON_STAT(efx, XgTxBroadcastPkts, tx_broadcast);
	FALCON_STAT(efx, XgTxUnicastPkts, tx_unicast);
	FALCON_STAT(efx, XgTxControlPkts, tx_control);
	FALCON_STAT(efx, XgTxPausePkts, tx_pause);
	FALCON_STAT(efx, XgTxPkts64Octets, tx_64);
	FALCON_STAT(efx, XgTxPkts65to127Octets, tx_65_to_127);
	FALCON_STAT(efx, XgTxPkts128to255Octets, tx_128_to_255);
	FALCON_STAT(efx, XgTxPkts256to511Octets, tx_256_to_511);
	FALCON_STAT(efx, XgTxPkts512to1023Octets, tx_512_to_1023);
	FALCON_STAT(efx, XgTxPkts1024to15xxOctets, tx_1024_to_15xx);
	FALCON_STAT(efx, XgTxPkts1519toMaxOctets, tx_15xx_to_jumbo);
	FALCON_STAT(efx, XgTxUndersizePkts, tx_lt64);
	FALCON_STAT(efx, XgTxOversizePkts, tx_gtjumbo);
	FALCON_STAT(efx, XgTxNonTcpUdpPkt, tx_non_tcpudp);
	FALCON_STAT(efx, XgTxMacSrcErrPkt, tx_mac_src_error);
	FALCON_STAT(efx, XgTxIpSrcErrPkt, tx_ip_src_error);

	/* Update derived statistics */
	mac_stats->tx_good_bytes =
		(mac_stats->tx_bytes - mac_stats->tx_bad_bytes);
	mac_stats->rx_bad_bytes =
		(mac_stats->rx_bytes - mac_stats->rx_good_bytes);
}

int falcon_check_xmac(struct efx_nic *efx)
{
	unsigned xaui_link_ok;
	int rc;

	falcon_mask_status_intr(efx, 0);
	xaui_link_ok = falcon_xaui_link_ok(efx);

	if (EFX_WORKAROUND_5147(efx) && !xaui_link_ok)
		(void) falcon_reset_xaui(efx);

	/* Call the PHY check_hw routine */
	rc = efx->phy_op->check_hw(efx);

	/* Unmask interrupt if everything was (and still is) ok */
	if (xaui_link_ok && efx->link_up)
		falcon_mask_status_intr(efx, 1);

	return rc;
}

/* Simulate a PHY event */
void falcon_xmac_sim_phy_event(struct efx_nic *efx)
{
	efx_qword_t phy_event;

	EFX_POPULATE_QWORD_2(phy_event,
			     EV_CODE, GLOBAL_EV_DECODE,
			     XG_PHY_INTR, 1);
	falcon_generate_event(&efx->channel[0], &phy_event);
}

int falcon_xmac_get_settings(struct efx_nic *efx, struct ethtool_cmd *ecmd)
{
	mdio_clause45_get_settings(efx, ecmd);
	ecmd->transceiver = XCVR_INTERNAL;
	ecmd->phy_address = efx->mii.phy_id;
	ecmd->autoneg = AUTONEG_DISABLE;
	ecmd->duplex = DUPLEX_FULL;
	return 0;
}

int falcon_xmac_set_settings(struct efx_nic *efx, struct ethtool_cmd *ecmd)
{
	if (ecmd->transceiver != XCVR_INTERNAL)
		return -EINVAL;
	if (ecmd->autoneg != AUTONEG_DISABLE)
		return -EINVAL;
	if (ecmd->duplex != DUPLEX_FULL)
		return -EINVAL;

	return mdio_clause45_set_settings(efx, ecmd);
}


int falcon_xmac_set_pause(struct efx_nic *efx, enum efx_fc_type flow_control)
{
	int reset;

	if (flow_control & EFX_FC_AUTO) {
		EFX_LOG(efx, "10G does not support flow control "
			"autonegotiation\n");
		return -EINVAL;
	}

	if ((flow_control & EFX_FC_TX) && !(flow_control & EFX_FC_RX))
		return -EINVAL;

	/* TX flow control may automatically turn itself off if the
	 * link partner (intermittently) stops responding to pause
	 * frames. There isn't any indication that this has happened,
	 * so the best we do is leave it up to the user to spot this
	 * and fix it be cycling transmit flow control on this end. */
	reset = ((flow_control & EFX_FC_TX) &&
		 !(efx->flow_control & EFX_FC_TX));
	if (EFX_WORKAROUND_11482(efx) && reset) {
		if (FALCON_REV(efx) >= FALCON_REV_B0) {
			/* Recover by resetting the EM block */
			if (efx->link_up)
				falcon_drain_tx_fifo(efx);
		} else {
			/* Schedule a reset to recover */
			efx_schedule_reset(efx, RESET_TYPE_INVISIBLE);
		}
	}

	efx->flow_control = flow_control;

	return 0;
}