From fa6031df12fcbc1cd21586576046d821f2cef2e2 Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Sun, 11 Oct 2020 11:09:42 +0200 Subject: [PATCH 1/3] macb: add RM9200's interrupt flag TBRE Transmit Buffer Register Empty replaces TXERR on RM9200 and signals the sender may try to send again becase the last queued frame is no longer in queue (being transmitted or already transmitted). Cc: Nicolas Ferre Cc: Claudiu Beznea Cc: Daniel Palmer Signed-off-by: Willy Tarreau Link: https://lore.kernel.org/r/20201011090944.10607-2-w@1wt.eu Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/cadence/macb.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h index 3fd5c6cc23af..1dbf7d86d267 100644 --- a/drivers/net/ethernet/cadence/macb.h +++ b/drivers/net/ethernet/cadence/macb.h @@ -366,6 +366,8 @@ #define MACB_ISR_RLE_SIZE 1 #define MACB_TXERR_OFFSET 6 /* EN TX frame corrupt from error interrupt */ #define MACB_TXERR_SIZE 1 +#define MACB_RM9200_TBRE_OFFSET 6 /* EN may send new frame interrupt (RM9200) */ +#define MACB_RM9200_TBRE_SIZE 1 #define MACB_TCOMP_OFFSET 7 /* Enable transmit complete interrupt */ #define MACB_TCOMP_SIZE 1 #define MACB_ISR_LINK_OFFSET 9 /* Enable link change interrupt */ From 73d7422813839bbcae3dd28ff0d3c48d916e0b57 Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Sun, 11 Oct 2020 11:09:43 +0200 Subject: [PATCH 2/3] macb: prepare at91 to use a 2-frame TX queue The RM9200 supports one frame being sent while another one is waiting in queue. This avoids the dead time that follows the emission of a frame and which prevents one from reaching line speed. Right now the driver supports only a single skb, so we'll first replace the rm9200-specific skb info with an array of two macb_tx_skb (already used by other drivers). This patch only moves the skb_length to txq[0].size and skb_physaddr to skb[0].mapping but doesn't perform any other change. It already uses [desc] in order to minimize future changes. Cc: Nicolas Ferre Cc: Claudiu Beznea Cc: Daniel Palmer Signed-off-by: Willy Tarreau Link: https://lore.kernel.org/r/20201011090944.10607-3-w@1wt.eu Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/cadence/macb.h | 6 ++--- drivers/net/ethernet/cadence/macb_main.c | 28 ++++++++++++++---------- 2 files changed, 18 insertions(+), 16 deletions(-) diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h index 1dbf7d86d267..4c4672ff66a3 100644 --- a/drivers/net/ethernet/cadence/macb.h +++ b/drivers/net/ethernet/cadence/macb.h @@ -1207,10 +1207,8 @@ struct macb { phy_interface_t phy_interface; - /* AT91RM9200 transmit */ - struct sk_buff *skb; /* holds skb until xmit interrupt completes */ - dma_addr_t skb_physaddr; /* phys addr from pci_map_single */ - int skb_length; /* saved skb length for pci_unmap_single */ + /* AT91RM9200 transmit queue (1 on wire + 1 queued) */ + struct macb_tx_skb rm9200_txq[2]; unsigned int max_tx_length; u64 ethtool_stats[GEM_STATS_LEN + QUEUE_STATS_LEN * MACB_MAX_QUEUES]; diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index 4b42b2d6398c..35d2f7f42e0b 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -3995,14 +3995,16 @@ static netdev_tx_t at91ether_start_xmit(struct sk_buff *skb, struct macb *lp = netdev_priv(dev); if (macb_readl(lp, TSR) & MACB_BIT(RM9200_BNQ)) { + int desc = 0; + netif_stop_queue(dev); /* Store packet information (to free when Tx completed) */ - lp->skb = skb; - lp->skb_length = skb->len; - lp->skb_physaddr = dma_map_single(&lp->pdev->dev, skb->data, - skb->len, DMA_TO_DEVICE); - if (dma_mapping_error(&lp->pdev->dev, lp->skb_physaddr)) { + lp->rm9200_txq[desc].skb = skb; + lp->rm9200_txq[desc].size = skb->len; + lp->rm9200_txq[desc].mapping = dma_map_single(&lp->pdev->dev, skb->data, + skb->len, DMA_TO_DEVICE); + if (dma_mapping_error(&lp->pdev->dev, lp->rm9200_txq[desc].mapping)) { dev_kfree_skb_any(skb); dev->stats.tx_dropped++; netdev_err(dev, "%s: DMA mapping error\n", __func__); @@ -4010,7 +4012,7 @@ static netdev_tx_t at91ether_start_xmit(struct sk_buff *skb, } /* Set address of the data in the Transmit Address register */ - macb_writel(lp, TAR, lp->skb_physaddr); + macb_writel(lp, TAR, lp->rm9200_txq[desc].mapping); /* Set length of the packet in the Transmit Control register */ macb_writel(lp, TCR, skb->len); @@ -4073,6 +4075,7 @@ static irqreturn_t at91ether_interrupt(int irq, void *dev_id) struct net_device *dev = dev_id; struct macb *lp = netdev_priv(dev); u32 intstatus, ctl; + unsigned int desc; /* MAC Interrupt Status register indicates what interrupts are pending. * It is automatically cleared once read. @@ -4089,13 +4092,14 @@ static irqreturn_t at91ether_interrupt(int irq, void *dev_id) if (intstatus & (MACB_BIT(ISR_TUND) | MACB_BIT(ISR_RLE))) dev->stats.tx_errors++; - if (lp->skb) { - dev_consume_skb_irq(lp->skb); - lp->skb = NULL; - dma_unmap_single(&lp->pdev->dev, lp->skb_physaddr, - lp->skb_length, DMA_TO_DEVICE); + desc = 0; + if (lp->rm9200_txq[desc].skb) { + dev_consume_skb_irq(lp->rm9200_txq[desc].skb); + lp->rm9200_txq[desc].skb = NULL; + dma_unmap_single(&lp->pdev->dev, lp->rm9200_txq[desc].mapping, + lp->rm9200_txq[desc].size, DMA_TO_DEVICE); dev->stats.tx_packets++; - dev->stats.tx_bytes += lp->skb_length; + dev->stats.tx_bytes += lp->rm9200_txq[desc].size; } netif_wake_queue(dev); } From 0a4e9ce17ba77847e5a9f87eed3c0ba46e3f82eb Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Sun, 11 Oct 2020 11:09:44 +0200 Subject: [PATCH 3/3] macb: support the two tx descriptors on at91rm9200 The at91rm9200 variant used by a few chips including the MSC313 supports two Tx descriptors (one frame being serialized and another one queued). However the driver only implemented a single one, which adds a dead time after each transfer to receive and process the interrupt and wake the queue up, preventing from reaching line rate. This patch implements a very basic 2-deep queue to address this limitation. The tests run on a Breadbee board equipped with an MSC313E show that at 1 GHz, HTTP traffic on medium-sized objects (45kB) was limited to exactly 50 Mbps before this patch, and jumped to 76 Mbps with this patch. And tests on a single TCP stream with an MTU of 576 jump from 10kpps to 15kpps. With 1500 byte packets it's now possible to reach line rate versus 75 Mbps before. Cc: Nicolas Ferre Cc: Claudiu Beznea Cc: Daniel Palmer Signed-off-by: Willy Tarreau Link: https://lore.kernel.org/r/20201011090944.10607-4-w@1wt.eu Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/cadence/macb.h | 2 ++ drivers/net/ethernet/cadence/macb_main.c | 46 +++++++++++++++++++----- 2 files changed, 40 insertions(+), 8 deletions(-) diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h index 4c4672ff66a3..5de47f6fde5a 100644 --- a/drivers/net/ethernet/cadence/macb.h +++ b/drivers/net/ethernet/cadence/macb.h @@ -1209,6 +1209,8 @@ struct macb { /* AT91RM9200 transmit queue (1 on wire + 1 queued) */ struct macb_tx_skb rm9200_txq[2]; + unsigned int rm9200_tx_tail; + unsigned int rm9200_tx_len; unsigned int max_tx_length; u64 ethtool_stats[GEM_STATS_LEN + QUEUE_STATS_LEN * MACB_MAX_QUEUES]; diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index 35d2f7f42e0b..883e47c5b1a7 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -3908,6 +3908,7 @@ static int at91ether_start(struct macb *lp) MACB_BIT(ISR_TUND) | MACB_BIT(ISR_RLE) | MACB_BIT(TCOMP) | + MACB_BIT(RM9200_TBRE) | MACB_BIT(ISR_ROVR) | MACB_BIT(HRESP)); @@ -3924,6 +3925,7 @@ static void at91ether_stop(struct macb *lp) MACB_BIT(ISR_TUND) | MACB_BIT(ISR_RLE) | MACB_BIT(TCOMP) | + MACB_BIT(RM9200_TBRE) | MACB_BIT(ISR_ROVR) | MACB_BIT(HRESP)); @@ -3993,11 +3995,10 @@ static netdev_tx_t at91ether_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct macb *lp = netdev_priv(dev); + unsigned long flags; - if (macb_readl(lp, TSR) & MACB_BIT(RM9200_BNQ)) { - int desc = 0; - - netif_stop_queue(dev); + if (lp->rm9200_tx_len < 2) { + int desc = lp->rm9200_tx_tail; /* Store packet information (to free when Tx completed) */ lp->rm9200_txq[desc].skb = skb; @@ -4011,6 +4012,15 @@ static netdev_tx_t at91ether_start_xmit(struct sk_buff *skb, return NETDEV_TX_OK; } + spin_lock_irqsave(&lp->lock, flags); + + lp->rm9200_tx_tail = (desc + 1) & 1; + lp->rm9200_tx_len++; + if (lp->rm9200_tx_len > 1) + netif_stop_queue(dev); + + spin_unlock_irqrestore(&lp->lock, flags); + /* Set address of the data in the Transmit Address register */ macb_writel(lp, TAR, lp->rm9200_txq[desc].mapping); /* Set length of the packet in the Transmit Control register */ @@ -4076,6 +4086,8 @@ static irqreturn_t at91ether_interrupt(int irq, void *dev_id) struct macb *lp = netdev_priv(dev); u32 intstatus, ctl; unsigned int desc; + unsigned int qlen; + u32 tsr; /* MAC Interrupt Status register indicates what interrupts are pending. * It is automatically cleared once read. @@ -4087,21 +4099,39 @@ static irqreturn_t at91ether_interrupt(int irq, void *dev_id) at91ether_rx(dev); /* Transmit complete */ - if (intstatus & MACB_BIT(TCOMP)) { + if (intstatus & (MACB_BIT(TCOMP) | MACB_BIT(RM9200_TBRE))) { /* The TCOM bit is set even if the transmission failed */ if (intstatus & (MACB_BIT(ISR_TUND) | MACB_BIT(ISR_RLE))) dev->stats.tx_errors++; - desc = 0; - if (lp->rm9200_txq[desc].skb) { + spin_lock(&lp->lock); + + tsr = macb_readl(lp, TSR); + + /* we have three possibilities here: + * - all pending packets transmitted (TGO, implies BNQ) + * - only first packet transmitted (!TGO && BNQ) + * - two frames pending (!TGO && !BNQ) + * Note that TGO ("transmit go") is called "IDLE" on RM9200. + */ + qlen = (tsr & MACB_BIT(TGO)) ? 0 : + (tsr & MACB_BIT(RM9200_BNQ)) ? 1 : 2; + + while (lp->rm9200_tx_len > qlen) { + desc = (lp->rm9200_tx_tail - lp->rm9200_tx_len) & 1; dev_consume_skb_irq(lp->rm9200_txq[desc].skb); lp->rm9200_txq[desc].skb = NULL; dma_unmap_single(&lp->pdev->dev, lp->rm9200_txq[desc].mapping, lp->rm9200_txq[desc].size, DMA_TO_DEVICE); dev->stats.tx_packets++; dev->stats.tx_bytes += lp->rm9200_txq[desc].size; + lp->rm9200_tx_len--; } - netif_wake_queue(dev); + + if (lp->rm9200_tx_len < 2 && netif_queue_stopped(dev)) + netif_wake_queue(dev); + + spin_unlock(&lp->lock); } /* Work-around for EMAC Errata section 41.3.1 */