[PATCH C 0/7] Freescale ethernet driver updates (part 3)

[PATCH C 0/7] Freescale ethernet driver updates (part 3)

[Russell King - ARM Linux]

David,

Here's the third batch of patches for the Freescale FEC ethernet driver,
based upon the previous set of patches.  This concludes the changes I
currently have prepared and have been reviewed for the next merge window
at this time.

Many thanks.

 drivers/net/ethernet/freescale/fec.h      |   9 +-
 drivers/net/ethernet/freescale/fec_main.c | 139 ++++++++++++++----------------
 2 files changed, 68 insertions(+), 80 deletions(-)

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[PATCH C 1/7] net: fec: better implementation of iMX6 ERR006358 quirk

[Russell King]

Using a (delayed) workqueue for ERR006358 is not correct - a work queue
is a single-trigger device.  Once the work queue has been scheduled, it
can't be re-scheduled until it has been run.  This can cause problems -
with an appropriate packet timing, we can end up with packets queued,
but not sent by the hardware, resulting in the transmit timeout firing.

Re-implement this as per the workaround detailed in the ERR006358
documentation - if there are packets waiting to be sent when we service
the transmit ring, and we see that the transmitter is not running,
kick the transmitter to run the pending entries in the ring.

Testing here with a 10Mbit half duplex link sees the resulting iperf
TCP bandwidth increase from between 1 to 2Mbps to between 8 to 9Mbps.

Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/net/ethernet/freescale/fec.h      |  1 -
 drivers/net/ethernet/freescale/fec_main.c | 30 ++++--------------------------
 2 files changed, 4 insertions(+), 27 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index 96d2a18f1b99..17e294970207 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -259,7 +259,6 @@ struct bufdesc_ex {
 struct fec_enet_delayed_work {
 	struct delayed_work delay_work;
 	bool timeout;
-	bool trig_tx;
 };
 
 /* The FEC buffer descriptors track the ring buffers.  The rx_bd_base and
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 9d82d915b06d..8cfc3a3de7fb 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -342,22 +342,6 @@ fec_enet_clear_csum(struct sk_buff *skb, struct net_device *ndev)
 	return 0;
 }
 
-static void
-fec_enet_submit_work(struct bufdesc *bdp, struct fec_enet_private *fep)
-{
-	const struct platform_device_id *id_entry =
-				platform_get_device_id(fep->pdev);
-	struct bufdesc *bdp_pre;
-
-	bdp_pre = fec_enet_get_prevdesc(bdp, fep);
-	if ((id_entry->driver_data & FEC_QUIRK_ERR006358) &&
-	    !(bdp_pre->cbd_sc & BD_ENET_TX_READY)) {
-		fep->delay_work.trig_tx = true;
-		schedule_delayed_work(&(fep->delay_work.delay_work),
-					msecs_to_jiffies(1));
-	}
-}
-
 static int
 fec_enet_txq_submit_frag_skb(struct sk_buff *skb, struct net_device *ndev)
 {
@@ -545,8 +529,6 @@ static int fec_enet_txq_submit_skb(struct sk_buff *skb, struct net_device *ndev)
 	status |= (BD_ENET_TX_READY | BD_ENET_TX_TC);
 	bdp->cbd_sc = status;
 
-	fec_enet_submit_work(bdp, fep);
-
 	/* If this was the last BD in the ring, start at the beginning again. */
 	bdp = fec_enet_get_nextdesc(last_bdp, fep);
 
@@ -735,8 +717,6 @@ static int fec_enet_txq_submit_tso(struct sk_buff *skb, struct net_device *ndev)
 	/* Save skb pointer */
 	fep->tx_skbuff[index] = skb;
 
-	fec_enet_submit_work(bdp, fep);
-
 	skb_tx_timestamp(skb);
 	fep->cur_tx = bdp;
 
@@ -1065,11 +1045,6 @@ static void fec_enet_work(struct work_struct *work)
 		}
 		rtnl_unlock();
 	}
-
-	if (fep->delay_work.trig_tx) {
-		fep->delay_work.trig_tx = false;
-		writel(0, fep->hwp + FEC_X_DES_ACTIVE);
-	}
 }
 
 static void
@@ -1166,7 +1141,10 @@ fec_enet_tx(struct net_device *ndev)
 				netif_wake_queue(ndev);
 		}
 	}
-	return;
+
+	/* ERR006538: Keep the transmitter going */
+	if (bdp != fep->cur_tx && readl(fep->hwp + FEC_X_DES_ACTIVE) == 0)
+		writel(0, fep->hwp + FEC_X_DES_ACTIVE);
 }
 
 /* During a receive, the cur_rx points to the current incoming buffer.
-- 
1.8.3.1

[PATCH C 2/7] net: fec: replace delayed work with standard work

[Russell King]

As of "better implementation of iMX6 ERR006358 quirk", we no longer have
a requirement for a delayed work.  Moreover, the work is now only used
for timeout purposes, so the timeout flag is also pointless - we set it
each time we queue the work, and the work clears it.

Replace the fec_enet_delayed_work struct with a standard work_struct,
resulting in simplified timeout handling code.

Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/net/ethernet/freescale/fec.h      |  8 ++------
 drivers/net/ethernet/freescale/fec_main.c | 34 +++++++++++++------------------
 2 files changed, 16 insertions(+), 26 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index 17e294970207..bd53caf1c1eb 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -256,11 +256,6 @@ struct bufdesc_ex {
 #define FLAG_RX_CSUM_ENABLED	(BD_ENET_RX_ICE | BD_ENET_RX_PCR)
 #define FLAG_RX_CSUM_ERROR	(BD_ENET_RX_ICE | BD_ENET_RX_PCR)
 
-struct fec_enet_delayed_work {
-	struct delayed_work delay_work;
-	bool timeout;
-};
-
 /* The FEC buffer descriptors track the ring buffers.  The rx_bd_base and
  * tx_bd_base always point to the base of the buffer descriptors.  The
  * cur_rx and cur_tx point to the currently available buffer.
@@ -326,6 +321,8 @@ struct fec_enet_private {
 	struct	napi_struct napi;
 	int	csum_flags;
 
+	struct work_struct tx_timeout_work;
+
 	struct ptp_clock *ptp_clock;
 	struct ptp_clock_info ptp_caps;
 	unsigned long last_overflow_check;
@@ -338,7 +335,6 @@ struct fec_enet_private {
 	int hwts_rx_en;
 	int hwts_tx_en;
 	struct timer_list time_keep;
-	struct fec_enet_delayed_work delay_work;
 	struct regulator *reg_phy;
 };
 
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 8cfc3a3de7fb..b2ae7e706d5e 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1020,31 +1020,25 @@ fec_timeout(struct net_device *ndev)
 
 	ndev->stats.tx_errors++;
 
-	fep->delay_work.timeout = true;
-	schedule_delayed_work(&(fep->delay_work.delay_work), 0);
+	schedule_work(&fep->tx_timeout_work);
 }
 
-static void fec_enet_work(struct work_struct *work)
+static void fec_enet_timeout_work(struct work_struct *work)
 {
 	struct fec_enet_private *fep =
-		container_of(work,
-			     struct fec_enet_private,
-			     delay_work.delay_work.work);
+		container_of(work, struct fec_enet_private, tx_timeout_work);
 	struct net_device *ndev = fep->netdev;
 
-	if (fep->delay_work.timeout) {
-		fep->delay_work.timeout = false;
-		rtnl_lock();
-		if (netif_device_present(ndev) || netif_running(ndev)) {
-			napi_disable(&fep->napi);
-			netif_tx_lock_bh(ndev);
-			fec_restart(ndev);
-			netif_wake_queue(ndev);
-			netif_tx_unlock_bh(ndev);
-			napi_enable(&fep->napi);
-		}
-		rtnl_unlock();
+	rtnl_lock();
+	if (netif_device_present(ndev) || netif_running(ndev)) {
+		napi_disable(&fep->napi);
+		netif_tx_lock_bh(ndev);
+		fec_restart(ndev);
+		netif_wake_queue(ndev);
+		netif_tx_unlock_bh(ndev);
+		napi_enable(&fep->napi);
 	}
+	rtnl_unlock();
 }
 
 static void
@@ -2642,7 +2636,7 @@ fec_probe(struct platform_device *pdev)
 	if (fep->bufdesc_ex && fep->ptp_clock)
 		netdev_info(ndev, "registered PHC device %d\n", fep->dev_id);
 
-	INIT_DELAYED_WORK(&(fep->delay_work.delay_work), fec_enet_work);
+	INIT_WORK(&fep->tx_timeout_work, fec_enet_timeout_work);
 	return 0;
 
 failed_register:
@@ -2667,7 +2661,7 @@ fec_drv_remove(struct platform_device *pdev)
 	struct net_device *ndev = platform_get_drvdata(pdev);
 	struct fec_enet_private *fep = netdev_priv(ndev);
 
-	cancel_delayed_work_sync(&(fep->delay_work.delay_work));
+	cancel_work_sync(&fep->tx_timeout_work);
 	unregister_netdev(ndev);
 	fec_enet_mii_remove(fep);
 	del_timer_sync(&fep->time_keep);
-- 
1.8.3.1

[PATCH C 3/7] net: fec: clear receive interrupts before processing a packet

[Russell King]

Clear any pending receive interrupt before we process a pending packet.
This helps to avoid any spurious interrupts being raised after we have
fully cleaned the receive ring, while still allowing an interrupt to be
raised if we receive another packet.

The position of this is critical: we must do this prior to reading the
next packet status to avoid potentially dropping an interrupt when a
packet is still pending.

Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/net/ethernet/freescale/fec_main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index b2ae7e706d5e..79d578d6db8a 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1184,6 +1184,8 @@ fec_enet_rx(struct net_device *ndev, int budget)
 		if ((status & BD_ENET_RX_LAST) == 0)
 			netdev_err(ndev, "rcv is not +last\n");
 
+		writel(FEC_ENET_RXF, fep->hwp + FEC_IEVENT);
+
 		/* Check for errors. */
 		if (status & (BD_ENET_RX_LG | BD_ENET_RX_SH | BD_ENET_RX_NO |
 			   BD_ENET_RX_CR | BD_ENET_RX_OV)) {
-- 
1.8.3.1

[PATCH C 4/7] net: fec: reorder ethtool ops to match order in struct declaration

[Russell King]

This allows us to merge two separate preprocessor conditionals together.

Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/net/ethernet/freescale/fec_main.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 79d578d6db8a..c6b1bf797a39 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -2014,21 +2014,19 @@ static int fec_enet_nway_reset(struct net_device *dev)
 }
 
 static const struct ethtool_ops fec_enet_ethtool_ops = {
-#if !defined(CONFIG_M5272)
-	.get_pauseparam		= fec_enet_get_pauseparam,
-	.set_pauseparam		= fec_enet_set_pauseparam,
-#endif
 	.get_settings		= fec_enet_get_settings,
 	.set_settings		= fec_enet_set_settings,
 	.get_drvinfo		= fec_enet_get_drvinfo,
-	.get_link		= ethtool_op_get_link,
-	.get_ts_info		= fec_enet_get_ts_info,
 	.nway_reset		= fec_enet_nway_reset,
+	.get_link		= ethtool_op_get_link,
 #ifndef CONFIG_M5272
-	.get_ethtool_stats	= fec_enet_get_ethtool_stats,
+	.get_pauseparam		= fec_enet_get_pauseparam,
+	.set_pauseparam		= fec_enet_set_pauseparam,
 	.get_strings		= fec_enet_get_strings,
+	.get_ethtool_stats	= fec_enet_get_ethtool_stats,
 	.get_sset_count		= fec_enet_get_sset_count,
 #endif
+	.get_ts_info		= fec_enet_get_ts_info,
 };
 
 static int fec_enet_ioctl(struct net_device *ndev, struct ifreq *rq, int cmd)
-- 
1.8.3.1

[PATCH C 5/7] net: fec: add support for dumping transmit ring on timeout

[Russell King]

When we timeout on transmit, it would be useful to dump the transmit
ring, so we can see the ring state.  This can be helpful to diagnose
the cause of transmit timeouts.

Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/net/ethernet/freescale/fec_main.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index c6b1bf797a39..09fcdc768931 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -320,6 +320,27 @@ static void *swap_buffer(void *bufaddr, int len)
 	return bufaddr;
 }
 
+static void fec_dump(struct net_device *ndev)
+{
+	struct fec_enet_private *fep = netdev_priv(ndev);
+	struct bufdesc *bdp = fep->tx_bd_base;
+	unsigned int index = 0;
+
+	netdev_info(ndev, "TX ring dump\n");
+	pr_info("Nr     SC     addr       len  SKB\n");
+
+	do {
+		pr_info("%3u %c%c 0x%04x 0x%08lx %4u %p\n",
+			index,
+			bdp == fep->cur_tx ? 'S' : ' ',
+			bdp == fep->dirty_tx ? 'H' : ' ',
+			bdp->cbd_sc, bdp->cbd_bufaddr, bdp->cbd_datlen,
+			fep->tx_skbuff[index]);
+		bdp = fec_enet_get_nextdesc(bdp, fep);
+		index++;
+	} while (bdp != fep->tx_bd_base);
+}
+
 static inline bool is_ipv4_pkt(struct sk_buff *skb)
 {
 	return skb->protocol == htons(ETH_P_IP) && ip_hdr(skb)->version == 4;
@@ -1018,6 +1039,8 @@ fec_timeout(struct net_device *ndev)
 {
 	struct fec_enet_private *fep = netdev_priv(ndev);
 
+	fec_dump(ndev);
+
 	ndev->stats.tx_errors++;
 
 	schedule_work(&fep->tx_timeout_work);
-- 
1.8.3.1

[PATCH C 6/7] net: fec: remove useless status check in tx reap path

[Russell King]

Remove a useless status check in the transmit reap path - we have
already checked that the BD_ENET_TX_READY bit is clear, and as the
hardware only ever clears this bit, there is no way this test can ever
be true.

Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/net/ethernet/freescale/fec_main.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 09fcdc768931..8679c919419c 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1133,9 +1133,6 @@ fec_enet_tx(struct net_device *ndev)
 			skb_tstamp_tx(skb, &shhwtstamps);
 		}
 
-		if (status & BD_ENET_TX_READY)
-			netdev_err(ndev, "HEY! Enet xmit interrupt and TX_READY\n");
-
 		/* Deferred means some collisions occurred during transmit,
 		 * but we eventually sent the packet OK.
 		 */
-- 
1.8.3.1

[PATCH C 7/7] net: fec: consolidate hwtstamp implementation

[Russell King]

Both transmit and receive use the same infrastructure for calculating
the packet timestamp.  Rather than duplicating the code, provide a
function to do this common work.  Model this function in the Intel
e1000e version which avoids calling ns_to_ktime() within the spinlock;
the spinlock is critical for timecounter_cyc2time() but not
ns_to_ktime().

Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/net/ethernet/freescale/fec_main.c | 37 ++++++++++++++++---------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 8679c919419c..e0efb212223f 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1065,6 +1065,21 @@ static void fec_enet_timeout_work(struct work_struct *work)
 }
 
 static void
+fec_enet_hwtstamp(struct fec_enet_private *fep, unsigned ts,
+	struct skb_shared_hwtstamps *hwtstamps)
+{
+	unsigned long flags;
+	u64 ns;
+
+	spin_lock_irqsave(&fep->tmreg_lock, flags);
+	ns = timecounter_cyc2time(&fep->tc, ts);
+	spin_unlock_irqrestore(&fep->tmreg_lock, flags);
+
+	memset(hwtstamps, 0, sizeof(*hwtstamps));
+	hwtstamps->hwtstamp = ns_to_ktime(ns);
+}
+
+static void
 fec_enet_tx(struct net_device *ndev)
 {
 	struct	fec_enet_private *fep;
@@ -1122,14 +1137,9 @@ fec_enet_tx(struct net_device *ndev)
 		if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS) &&
 			fep->bufdesc_ex) {
 			struct skb_shared_hwtstamps shhwtstamps;
-			unsigned long flags;
 			struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
 
-			memset(&shhwtstamps, 0, sizeof(shhwtstamps));
-			spin_lock_irqsave(&fep->tmreg_lock, flags);
-			shhwtstamps.hwtstamp = ns_to_ktime(
-				timecounter_cyc2time(&fep->tc, ebdp->ts));
-			spin_unlock_irqrestore(&fep->tmreg_lock, flags);
+			fec_enet_hwtstamp(fep, ebdp->ts, &shhwtstamps);
 			skb_tstamp_tx(skb, &shhwtstamps);
 		}
 
@@ -1288,18 +1298,9 @@ fec_enet_rx(struct net_device *ndev, int budget)
 			skb->protocol = eth_type_trans(skb, ndev);
 
 			/* Get receive timestamp from the skb */
-			if (fep->hwts_rx_en && fep->bufdesc_ex) {
-				struct skb_shared_hwtstamps *shhwtstamps =
-							    skb_hwtstamps(skb);
-				unsigned long flags;
-
-				memset(shhwtstamps, 0, sizeof(*shhwtstamps));
-
-				spin_lock_irqsave(&fep->tmreg_lock, flags);
-				shhwtstamps->hwtstamp = ns_to_ktime(
-				    timecounter_cyc2time(&fep->tc, ebdp->ts));
-				spin_unlock_irqrestore(&fep->tmreg_lock, flags);
-			}
+			if (fep->hwts_rx_en && fep->bufdesc_ex)
+				fec_enet_hwtstamp(fep, ebdp->ts,
+						  skb_hwtstamps(skb));
 
 			if (fep->bufdesc_ex &&
 			    (fep->csum_flags & FLAG_RX_CSUM_ENABLED)) {
-- 
1.8.3.1

[PATCH C 0/7] Freescale ethernet driver updates (part 3)

[David Miller]

From: Russell King - ARM Linux <linux@arm.linux.org.uk>
Date: Tue, 8 Jul 2014 13:01:17 +0100

> Here's the third batch of patches for the Freescale FEC ethernet driver,
> based upon the previous set of patches.  This concludes the changes I
> currently have prepared and have been reviewed for the next merge window
> at this time.

Series applied, thanks Russell.

[PATCH C 1/7] net: fec: better implementation of iMX6 ERR006358 quirk

[Russell King]

Using a (delayed) workqueue for ERR006358 is not correct - a work queue
is a single-trigger device.  Once the work queue has been scheduled, it
can't be re-scheduled until it has been run.  This can cause problems -
with an appropriate packet timing, we can end up with packets queued,
but not sent by the hardware, resulting in the transmit timeout firing.

Re-implement this as per the workaround detailed in the ERR006358
documentation - if there are packets waiting to be sent when we service
the transmit ring, and we see that the transmitter is not running,
kick the transmitter to run the pending entries in the ring.

Testing here with a 10Mbit half duplex link sees the resulting iperf
TCP bandwidth increase from between 1 to 2Mbps to between 8 to 9Mbps.

Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/net/ethernet/freescale/fec.h      |  1 -
 drivers/net/ethernet/freescale/fec_main.c | 30 ++++--------------------------
 2 files changed, 4 insertions(+), 27 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index 96d2a18f1b99..17e294970207 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -259,7 +259,6 @@ struct bufdesc_ex {
 struct fec_enet_delayed_work {
 	struct delayed_work delay_work;
 	bool timeout;
-	bool trig_tx;
 };
 
 /* The FEC buffer descriptors track the ring buffers.  The rx_bd_base and
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 9d82d915b06d..8cfc3a3de7fb 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -342,22 +342,6 @@ fec_enet_clear_csum(struct sk_buff *skb, struct net_device *ndev)
 	return 0;
 }
 
-static void
-fec_enet_submit_work(struct bufdesc *bdp, struct fec_enet_private *fep)
-{
-	const struct platform_device_id *id_entry =
-				platform_get_device_id(fep->pdev);
-	struct bufdesc *bdp_pre;
-
-	bdp_pre = fec_enet_get_prevdesc(bdp, fep);
-	if ((id_entry->driver_data & FEC_QUIRK_ERR006358) &&
-	    !(bdp_pre->cbd_sc & BD_ENET_TX_READY)) {
-		fep->delay_work.trig_tx = true;
-		schedule_delayed_work(&(fep->delay_work.delay_work),
-					msecs_to_jiffies(1));
-	}
-}
-
 static int
 fec_enet_txq_submit_frag_skb(struct sk_buff *skb, struct net_device *ndev)
 {
@@ -545,8 +529,6 @@ static int fec_enet_txq_submit_skb(struct sk_buff *skb, struct net_device *ndev)
 	status |= (BD_ENET_TX_READY | BD_ENET_TX_TC);
 	bdp->cbd_sc = status;
 
-	fec_enet_submit_work(bdp, fep);
-
 	/* If this was the last BD in the ring, start at the beginning again. */
 	bdp = fec_enet_get_nextdesc(last_bdp, fep);
 
@@ -735,8 +717,6 @@ static int fec_enet_txq_submit_tso(struct sk_buff *skb, struct net_device *ndev)
 	/* Save skb pointer */
 	fep->tx_skbuff[index] = skb;
 
-	fec_enet_submit_work(bdp, fep);
-
 	skb_tx_timestamp(skb);
 	fep->cur_tx = bdp;
 
@@ -1065,11 +1045,6 @@ static void fec_enet_work(struct work_struct *work)
 		}
 		rtnl_unlock();
 	}
-
-	if (fep->delay_work.trig_tx) {
-		fep->delay_work.trig_tx = false;
-		writel(0, fep->hwp + FEC_X_DES_ACTIVE);
-	}
 }
 
 static void
@@ -1166,7 +1141,10 @@ fec_enet_tx(struct net_device *ndev)
 				netif_wake_queue(ndev);
 		}
 	}
-	return;
+
+	/* ERR006538: Keep the transmitter going */
+	if (bdp != fep->cur_tx && readl(fep->hwp + FEC_X_DES_ACTIVE) == 0)
+		writel(0, fep->hwp + FEC_X_DES_ACTIVE);
 }
 
 /* During a receive, the cur_rx points to the current incoming buffer.
-- 
1.8.3.1

[PATCH C 1/7] net: fec: better implementation of iMX6 ERR006358 quirk

[Russell King - ARM Linux]

On Wed, Jul 09, 2014 at 10:30:11AM +0100, Russell King wrote:
> Using a (delayed) workqueue for ERR006358 is not correct - a work queue
> is a single-trigger device.  Once the work queue has been scheduled, it
> can't be re-scheduled until it has been run.  This can cause problems -
> with an appropriate packet timing, we can end up with packets queued,
> but not sent by the hardware, resulting in the transmit timeout firing.

Oops, please ignore this patch; re-sent in error.

-- 
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improving, and getting towards what was expected from it.