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net: fec: Add Scatter/gather support
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Add Scatter/gather support for FEC.
This feature allows to improve outbound throughput performance.

Tested on imx6dl sabresd board:
Running iperf tests shows a 55.4% improvement.

$ ethtool -K eth0 sg off
$ iperf -c 10.192.242.167 -t 3 &
[  3] local 10.192.242.108 port 52618 connected with 10.192.242.167 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 3.0 sec  99.5 MBytes   278 Mbits/sec

$ ethtool -K eth0 sg on
$ iperf -c 10.192.242.167 -t 3 &
[  3] local 10.192.242.108 port 52617 connected with 10.192.242.167 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 3.0 sec   154 MBytes   432 Mbits/sec

CC: Li Frank <B20596@freescale.com>
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Nimrod Andy authored and David S. Miller committed Jun 12, 2014
1 parent 55d0218 commit 6e90928
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Showing 2 changed files with 178 additions and 62 deletions.
2 changes: 1 addition & 1 deletion drivers/net/ethernet/freescale/fec.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -221,7 +221,7 @@ struct bufdesc_ex {
#define BD_ENET_TX_RCMASK ((ushort)0x003c)
#define BD_ENET_TX_UN ((ushort)0x0002)
#define BD_ENET_TX_CSL ((ushort)0x0001)
#define BD_ENET_TX_STATS ((ushort)0x03ff) /* All status bits */
#define BD_ENET_TX_STATS ((ushort)0x0fff) /* All status bits */

/*enhanced buffer descriptor control/status used by Ethernet transmit*/
#define BD_ENET_TX_INT 0x40000000
Expand Down
238 changes: 177 additions & 61 deletions drivers/net/ethernet/freescale/fec_main.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -289,6 +289,16 @@ static int fec_enet_get_bd_index(struct bufdesc *base, struct bufdesc *bdp,
return ((const char *)bdp - (const char *)base) / fep->bufdesc_size;
}

static int fec_enet_get_free_txdesc_num(struct fec_enet_private *fep)
{
int entries;

entries = ((const char *)fep->dirty_tx -
(const char *)fep->cur_tx) / fep->bufdesc_size - 1;

return entries > 0 ? entries : entries + fep->tx_ring_size;
}

static void *swap_buffer(void *bufaddr, int len)
{
int i;
Expand Down Expand Up @@ -316,103 +326,203 @@ fec_enet_clear_csum(struct sk_buff *skb, struct net_device *ndev)
return 0;
}

static int txq_submit_skb(struct sk_buff *skb, struct net_device *ndev)
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)
{
struct fec_enet_private *fep = netdev_priv(ndev);
const struct platform_device_id *id_entry =
platform_get_device_id(fep->pdev);
struct bufdesc *bdp, *bdp_pre;
void *bufaddr;
unsigned short status;
struct bufdesc *bdp = fep->cur_tx;
struct bufdesc_ex *ebdp;
int nr_frags = skb_shinfo(skb)->nr_frags;
int frag, frag_len;
unsigned short status;
unsigned int estatus = 0;
skb_frag_t *this_frag;
unsigned int index;
void *bufaddr;
int i;

/* Fill in a Tx ring entry */
for (frag = 0; frag < nr_frags; frag++) {
this_frag = &skb_shinfo(skb)->frags[frag];
bdp = fec_enet_get_nextdesc(bdp, fep);
ebdp = (struct bufdesc_ex *)bdp;

status = bdp->cbd_sc;
status &= ~BD_ENET_TX_STATS;
status |= (BD_ENET_TX_TC | BD_ENET_TX_READY);
frag_len = skb_shinfo(skb)->frags[frag].size;

/* Handle the last BD specially */
if (frag == nr_frags - 1) {
status |= (BD_ENET_TX_INTR | BD_ENET_TX_LAST);
if (fep->bufdesc_ex) {
estatus |= BD_ENET_TX_INT;
if (unlikely(skb_shinfo(skb)->tx_flags &
SKBTX_HW_TSTAMP && fep->hwts_tx_en))
estatus |= BD_ENET_TX_TS;
}
}

if (fep->bufdesc_ex) {
if (skb->ip_summed == CHECKSUM_PARTIAL)
estatus |= BD_ENET_TX_PINS | BD_ENET_TX_IINS;
ebdp->cbd_bdu = 0;
ebdp->cbd_esc = estatus;
}

bufaddr = page_address(this_frag->page.p) + this_frag->page_offset;

index = fec_enet_get_bd_index(fep->tx_bd_base, bdp, fep);
if (((unsigned long) bufaddr) & FEC_ALIGNMENT ||
id_entry->driver_data & FEC_QUIRK_SWAP_FRAME) {
memcpy(fep->tx_bounce[index], bufaddr, frag_len);
bufaddr = fep->tx_bounce[index];

if (id_entry->driver_data & FEC_QUIRK_SWAP_FRAME)
swap_buffer(bufaddr, frag_len);
}

bdp->cbd_bufaddr = dma_map_single(&fep->pdev->dev, bufaddr,
frag_len, DMA_TO_DEVICE);
if (dma_mapping_error(&fep->pdev->dev, bdp->cbd_bufaddr)) {
dev_kfree_skb_any(skb);
if (net_ratelimit())
netdev_err(ndev, "Tx DMA memory map failed\n");
goto dma_mapping_error;
}

bdp->cbd_datlen = frag_len;
bdp->cbd_sc = status;
}

fep->cur_tx = bdp;

return 0;

dma_mapping_error:
bdp = fep->cur_tx;
for (i = 0; i < frag; i++) {
bdp = fec_enet_get_nextdesc(bdp, fep);
dma_unmap_single(&fep->pdev->dev, bdp->cbd_bufaddr,
bdp->cbd_datlen, DMA_TO_DEVICE);
}
return NETDEV_TX_OK;
}

status = bdp->cbd_sc;
static int fec_enet_txq_submit_skb(struct sk_buff *skb, struct net_device *ndev)
{
struct fec_enet_private *fep = netdev_priv(ndev);
const struct platform_device_id *id_entry =
platform_get_device_id(fep->pdev);
int nr_frags = skb_shinfo(skb)->nr_frags;
struct bufdesc *bdp, *last_bdp;
void *bufaddr;
unsigned short status;
unsigned short buflen;
unsigned int estatus = 0;
unsigned int index;
int ret;

/* Protocol checksum off-load for TCP and UDP. */
if (fec_enet_clear_csum(skb, ndev)) {
dev_kfree_skb_any(skb);
return NETDEV_TX_OK;
}

/* Clear all of the status flags */
/* Fill in a Tx ring entry */
bdp = fep->cur_tx;
status = bdp->cbd_sc;
status &= ~BD_ENET_TX_STATS;

/* Set buffer length and buffer pointer */
bufaddr = skb->data;
bdp->cbd_datlen = skb->len;
buflen = skb_headlen(skb);

index = fec_enet_get_bd_index(fep->tx_bd_base, bdp, fep);

if (((unsigned long) bufaddr) & FEC_ALIGNMENT) {
memcpy(fep->tx_bounce[index], skb->data, skb->len);
if (((unsigned long) bufaddr) & FEC_ALIGNMENT ||
id_entry->driver_data & FEC_QUIRK_SWAP_FRAME) {
memcpy(fep->tx_bounce[index], skb->data, buflen);
bufaddr = fep->tx_bounce[index];
}

/*
* Some design made an incorrect assumption on endian mode of
* the system that it's running on. As the result, driver has to
* swap every frame going to and coming from the controller.
*/
if (id_entry->driver_data & FEC_QUIRK_SWAP_FRAME)
swap_buffer(bufaddr, skb->len);

/* Save skb pointer */
fep->tx_skbuff[index] = skb;
if (id_entry->driver_data & FEC_QUIRK_SWAP_FRAME)
swap_buffer(bufaddr, buflen);
}

/* Push the data cache so the CPM does not get stale memory
* data.
*/
bdp->cbd_bufaddr = dma_map_single(&fep->pdev->dev, bufaddr,
skb->len, DMA_TO_DEVICE);
buflen, DMA_TO_DEVICE);
if (dma_mapping_error(&fep->pdev->dev, bdp->cbd_bufaddr)) {
bdp->cbd_bufaddr = 0;
fep->tx_skbuff[index] = NULL;
dev_kfree_skb_any(skb);
if (net_ratelimit())
netdev_err(ndev, "Tx DMA memory map failed\n");
return NETDEV_TX_OK;
}

if (nr_frags) {
ret = fec_enet_txq_submit_frag_skb(skb, ndev);
if (ret)
return ret;
} else {
status |= (BD_ENET_TX_INTR | BD_ENET_TX_LAST);
if (fep->bufdesc_ex) {
estatus = BD_ENET_TX_INT;
if (unlikely(skb_shinfo(skb)->tx_flags &
SKBTX_HW_TSTAMP && fep->hwts_tx_en))
estatus |= BD_ENET_TX_TS;
}
}

if (fep->bufdesc_ex) {

struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
ebdp->cbd_bdu = 0;

if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP &&
fep->hwts_tx_en)) {
ebdp->cbd_esc = (BD_ENET_TX_TS | BD_ENET_TX_INT);
fep->hwts_tx_en))
skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
} else {
ebdp->cbd_esc = BD_ENET_TX_INT;

/* Enable protocol checksum flags
* We do not bother with the IP Checksum bits as they
* are done by the kernel
*/
if (skb->ip_summed == CHECKSUM_PARTIAL)
ebdp->cbd_esc |= BD_ENET_TX_PINS | BD_ENET_TX_IINS;
}
if (skb->ip_summed == CHECKSUM_PARTIAL)
estatus |= BD_ENET_TX_PINS | BD_ENET_TX_IINS;

ebdp->cbd_bdu = 0;
ebdp->cbd_esc = estatus;
}

last_bdp = fep->cur_tx;
index = fec_enet_get_bd_index(fep->tx_bd_base, last_bdp, fep);
/* Save skb pointer */
fep->tx_skbuff[index] = skb;

bdp->cbd_datlen = buflen;

/* Send it on its way. Tell FEC it's ready, interrupt when done,
* it's the last BD of the frame, and to put the CRC on the end.
*/
status |= (BD_ENET_TX_READY | BD_ENET_TX_INTR
| BD_ENET_TX_LAST | BD_ENET_TX_TC);
status |= (BD_ENET_TX_READY | BD_ENET_TX_TC);
bdp->cbd_sc = status;

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));
}
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(bdp, fep);
bdp = fec_enet_get_nextdesc(last_bdp, fep);

skb_tx_timestamp(skb);

Expand All @@ -421,7 +531,7 @@ static int txq_submit_skb(struct sk_buff *skb, struct net_device *ndev)
/* Trigger transmission start */
writel(0, fep->hwp + FEC_X_DES_ACTIVE);

return NETDEV_TX_OK;
return 0;
}

static netdev_tx_t
Expand All @@ -430,6 +540,7 @@ fec_enet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
struct fec_enet_private *fep = netdev_priv(ndev);
struct bufdesc *bdp;
unsigned short status;
int entries_free;
int ret;

/* Fill in a Tx ring entry */
Expand All @@ -441,15 +552,17 @@ fec_enet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
/* Ooops. All transmit buffers are full. Bail out.
* This should not happen, since ndev->tbusy should be set.
*/
netdev_err(ndev, "tx queue full!\n");
if (net_ratelimit())
netdev_err(ndev, "tx queue full!\n");
return NETDEV_TX_BUSY;
}

ret = txq_submit_skb(skb, ndev);
if (ret == -EBUSY)
return NETDEV_TX_BUSY;
ret = fec_enet_txq_submit_skb(skb, ndev);
if (ret)
return ret;

if (fep->cur_tx == fep->dirty_tx)
entries_free = fec_enet_get_free_txdesc_num(fep);
if (entries_free < MAX_SKB_FRAGS + 1)
netif_stop_queue(ndev);

return NETDEV_TX_OK;
Expand Down Expand Up @@ -770,6 +883,7 @@ fec_enet_tx(struct net_device *ndev)
unsigned short status;
struct sk_buff *skb;
int index = 0;
int entries;

fep = netdev_priv(ndev);
bdp = fep->dirty_tx;
Expand All @@ -786,9 +900,13 @@ fec_enet_tx(struct net_device *ndev)
index = fec_enet_get_bd_index(fep->tx_bd_base, bdp, fep);

skb = fep->tx_skbuff[index];
dma_unmap_single(&fep->pdev->dev, bdp->cbd_bufaddr, skb->len,
dma_unmap_single(&fep->pdev->dev, bdp->cbd_bufaddr, bdp->cbd_datlen,
DMA_TO_DEVICE);
bdp->cbd_bufaddr = 0;
if (!skb) {
bdp = fec_enet_get_nextdesc(bdp, fep);
continue;
}

/* Check for errors. */
if (status & (BD_ENET_TX_HB | BD_ENET_TX_LC |
Expand All @@ -807,7 +925,7 @@ fec_enet_tx(struct net_device *ndev)
ndev->stats.tx_carrier_errors++;
} else {
ndev->stats.tx_packets++;
ndev->stats.tx_bytes += bdp->cbd_datlen;
ndev->stats.tx_bytes += skb->len;
}

if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS) &&
Expand Down Expand Up @@ -844,15 +962,13 @@ fec_enet_tx(struct net_device *ndev)

/* Since we have freed up a buffer, the ring is no longer full
*/
if (fep->dirty_tx != fep->cur_tx) {
if (netif_queue_stopped(ndev))
netif_wake_queue(ndev);
}
entries = fec_enet_get_free_txdesc_num(fep);
if (entries >= MAX_SKB_FRAGS + 1 && netif_queue_stopped(ndev))
netif_wake_queue(ndev);
}
return;
}


/* During a receive, the cur_rx points to the current incoming buffer.
* When we update through the ring, if the next incoming buffer has
* not been given to the system, we just set the empty indicator,
Expand Down Expand Up @@ -2095,7 +2211,7 @@ static int fec_enet_init(struct net_device *ndev)
if (id_entry->driver_data & FEC_QUIRK_HAS_CSUM) {
/* enable hw accelerator */
ndev->features |= (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM
| NETIF_F_RXCSUM);
| NETIF_F_RXCSUM | NETIF_F_SG);
fep->csum_flags |= FLAG_RX_CSUM_ENABLED;
}

Expand Down

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