diff options
Diffstat (limited to 'target/linux/leon/patches/024-greth_resolve_smp_and_other_issues.patch')
| -rw-r--r-- | target/linux/leon/patches/024-greth_resolve_smp_and_other_issues.patch | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/target/linux/leon/patches/024-greth_resolve_smp_and_other_issues.patch b/target/linux/leon/patches/024-greth_resolve_smp_and_other_issues.patch new file mode 100644 index 000000000..c2293cae0 --- /dev/null +++ b/target/linux/leon/patches/024-greth_resolve_smp_and_other_issues.patch @@ -0,0 +1,399 @@ +From 4439d933884ee3c7e320b8d33bd2e268dd5b6fa5 Mon Sep 17 00:00:00 2001 +From: Daniel Hellstrom <daniel@gaisler.com> +Date: Wed, 1 Dec 2010 11:40:19 +0100 +Subject: [PATCH] GRETH: resolve SMP issues and other problems + +Fixes the following: +1. POLL should not enable IRQ when work is not completed +2. No locking between TX descriptor cleaning and XMIT descriptor handling +3. No locking between RX POLL and XMIT modifying control register +4. Since TX cleaning (called from POLL) is running in parallel with XMIT + unnecessary locking is needed. +5. IRQ handler looks at RX frame status solely, this is wrong when IRQ is + temporarily disabled (in POLL), and when IRQ is shared. +6. IRQ handler clears IRQ status, which is unnecessary +7. TX queue was stopped in preventing cause when not MAX_SKB_FRAGS+1 descriptors + were available after a SKB been scheduled by XMIT. Instead the TX queue is + stopped first when not enough descriptors are available upon entering XMIT. + +It was hard to split up this patch in smaller pieces since all are tied +together somehow. + +Note the RX flag used in the interrupt handler does not signal that interrtupt +was asserted, but that a frame was received. Same goes for TX. Also, IRQ is not +asserted when the RX flag is set before enabling IRQ enable until a new frame is +received. So extra care must be taken to avoid enabling IRQ and all descriptors +are already used, hence dead lock will upon us. See new POLL implementation that +enableds IRQ then look at the RX flag to determine if one or more IRQs may have +been missed. TX/RX flags are cleared before handling previously enabled +descriptors, this ensures that the RX/TX flags are valid when determining if IRQ +should be turned on again. + +By moving TX cleaning from POLL to XMIT in the standard case, removes some +locking trouble. Enabling TX cleaning from poll only when not enough TX +descriptors are available is safe because the TX queue is at the same time +stopped, thus XMIT will not be called. The TX queue is woken up again when +enough descriptrs are available. + +TX Frames are always enabled with IRQ, however the TX IRQ Enable flag will not +be enabled until XMIT must wait for free descriptors. + +Locking RX and XMIT parts of the driver from each other is needed because the +RX/TX enable bits share the same register. + +Signed-off-by: Daniel Hellstrom <daniel@gaisler.com> +--- + drivers/net/greth.c | 158 ++++++++++++++++++++++++++++++--------------------- + 1 files changed, 93 insertions(+), 65 deletions(-) + +--- a/drivers/net/greth.c ++++ b/drivers/net/greth.c +@@ -1,7 +1,7 @@ + /* + * Aeroflex Gaisler GRETH 10/100/1G Ethernet MAC. + * +- * 2005-2009 (c) Aeroflex Gaisler AB ++ * 2005-2010 (c) Aeroflex Gaisler AB + * + * This driver supports GRETH 10/100 and GRETH 10/100/1G Ethernet MACs + * available in the GRLIB VHDL IP core library. +@@ -401,12 +401,20 @@ greth_start_xmit(struct sk_buff *skb, st + struct greth_private *greth = netdev_priv(dev); + struct greth_bd *bdp; + int err = NETDEV_TX_OK; +- u32 status, dma_addr; ++ u32 status, dma_addr, ctrl; ++ unsigned long flags; + +- bdp = greth->tx_bd_base + greth->tx_next; ++ /* Clean TX Ring */ ++ greth_clean_tx(greth->netdev); + + if (unlikely(greth->tx_free <= 0)) { ++ spin_lock_irqsave(&greth->devlock, flags); /*save from poll/irq*/ ++ ctrl = GRETH_REGLOAD(greth->regs->control); ++ /* Enable TX IRQ only if not already in poll() routine */ ++ if ( ctrl & GRETH_RXI ) ++ GRETH_REGSAVE(greth->regs->control, ctrl | GRETH_TXI); + netif_stop_queue(dev); ++ spin_unlock_irqrestore(&greth->devlock, flags); + return NETDEV_TX_BUSY; + } + +@@ -419,13 +427,14 @@ greth_start_xmit(struct sk_buff *skb, st + goto out; + } + ++ bdp = greth->tx_bd_base + greth->tx_next; + dma_addr = greth_read_bd(&bdp->addr); + + memcpy((unsigned char *) phys_to_virt(dma_addr), skb->data, skb->len); + + dma_sync_single_for_device(greth->dev, dma_addr, skb->len, DMA_TO_DEVICE); + +- status = GRETH_BD_EN | (skb->len & GRETH_BD_LEN); ++ status = GRETH_BD_EN | GRETH_BD_IE | (skb->len & GRETH_BD_LEN); + + /* Wrap around descriptor ring */ + if (greth->tx_next == GRETH_TXBD_NUM_MASK) { +@@ -435,22 +444,11 @@ greth_start_xmit(struct sk_buff *skb, st + greth->tx_next = NEXT_TX(greth->tx_next); + greth->tx_free--; + +- /* No more descriptors */ +- if (unlikely(greth->tx_free == 0)) { +- +- /* Free transmitted descriptors */ +- greth_clean_tx(dev); +- +- /* If nothing was cleaned, stop queue & wait for irq */ +- if (unlikely(greth->tx_free == 0)) { +- status |= GRETH_BD_IE; +- netif_stop_queue(dev); +- } +- } +- + /* Write descriptor control word and enable transmission */ + greth_write_bd(&bdp->stat, status); ++ spin_lock_irqsave(&greth->devlock, flags); /*save from poll/irq*/ + greth_enable_tx(greth); ++ spin_unlock_irqrestore(&greth->devlock, flags); + + out: + dev_kfree_skb(skb); +@@ -463,13 +461,24 @@ greth_start_xmit_gbit(struct sk_buff *sk + { + struct greth_private *greth = netdev_priv(dev); + struct greth_bd *bdp; +- u32 status = 0, dma_addr; ++ u32 status = 0, dma_addr, ctrl; + int curr_tx, nr_frags, i, err = NETDEV_TX_OK; ++ unsigned long flags; + + nr_frags = skb_shinfo(skb)->nr_frags; + ++ /* Clean TX Ring */ ++ greth_clean_tx_gbit(dev); ++ + if (greth->tx_free < nr_frags + 1) { ++ spin_lock_irqsave(&greth->devlock, flags); /*save from poll/irq*/ ++ ctrl = GRETH_REGLOAD(greth->regs->control); ++ /* Enable TX IRQ only if not already in poll() routine */ ++ if ( ctrl & GRETH_RXI ) { ++ GRETH_REGSAVE(greth->regs->control, ctrl | GRETH_TXI); ++ } + netif_stop_queue(dev); ++ spin_unlock_irqrestore(&greth->devlock, flags); + err = NETDEV_TX_BUSY; + goto out; + } +@@ -522,14 +531,8 @@ greth_start_xmit_gbit(struct sk_buff *sk + /* More fragments left */ + if (i < nr_frags - 1) + status |= GRETH_TXBD_MORE; +- +- /* ... last fragment, check if out of descriptors */ +- else if (greth->tx_free - nr_frags - 1 < (MAX_SKB_FRAGS + 1)) { +- +- /* Enable interrupts and stop queue */ +- status |= GRETH_BD_IE; +- netif_stop_queue(dev); +- } ++ else ++ status |= GRETH_BD_IE; /* enable IRQ on last fragment */ + + greth_write_bd(&bdp->stat, status); + +@@ -557,7 +560,9 @@ greth_start_xmit_gbit(struct sk_buff *sk + + wmb(); + ++ spin_lock_irqsave(&greth->devlock, flags); /*save from poll/irq*/ + greth_enable_tx(greth); ++ spin_unlock_irqrestore(&greth->devlock, flags); + + return NETDEV_TX_OK; + +@@ -579,12 +584,11 @@ out: + return err; + } + +- + static irqreturn_t greth_interrupt(int irq, void *dev_id) + { + struct net_device *dev = dev_id; + struct greth_private *greth; +- u32 status; ++ u32 status, ctrl; + irqreturn_t retval = IRQ_NONE; + + greth = netdev_priv(dev); +@@ -594,13 +598,14 @@ static irqreturn_t greth_interrupt(int i + /* Get the interrupt events that caused us to be here. */ + status = GRETH_REGLOAD(greth->regs->status); + +- /* Handle rx and tx interrupts through poll */ +- if (status & (GRETH_INT_RE | GRETH_INT_RX | GRETH_INT_TE | GRETH_INT_TX)) { ++ /* Must see if interrupts are enabled also, INT_TX|INT_RX flags may be set regardless ++ * of whether IRQ is enabled or not. Especially important when shared IRQ. ++ */ ++ ctrl = GRETH_REGLOAD(greth->regs->control); + +- /* Clear interrupt status */ +- GRETH_REGSAVE(greth->regs->status, +- status & (GRETH_INT_RE | GRETH_INT_RX | +- GRETH_INT_TE | GRETH_INT_TX)); ++ /* Handle rx and tx interrupts through poll */ ++ if (((status & (GRETH_INT_RE | GRETH_INT_RX)) && (ctrl & GRETH_RXI)) || ++ ((status & (GRETH_INT_TE | GRETH_INT_TX)) && (ctrl & GRETH_TXI))) { + + retval = IRQ_HANDLED; + +@@ -625,6 +630,8 @@ static void greth_clean_tx(struct net_de + + while (1) { + bdp = greth->tx_bd_base + greth->tx_last; ++ GRETH_REGSAVE(greth->regs->status, GRETH_INT_TE | GRETH_INT_TX); ++ mb(); + stat = greth_read_bd(&bdp->stat); + + if (unlikely(stat & GRETH_BD_EN)) +@@ -685,7 +692,10 @@ static void greth_clean_tx_gbit(struct n + + /* We only clean fully completed SKBs */ + bdp_last_frag = greth->tx_bd_base + SKIP_TX(greth->tx_last, nr_frags); +- stat = bdp_last_frag->stat; ++ ++ GRETH_REGSAVE(greth->regs->status, GRETH_INT_TE | GRETH_INT_TX); ++ mb(); ++ stat = greth_read_bd(&bdp_last_frag->stat); + + if (stat & GRETH_BD_EN) + break; +@@ -717,23 +727,12 @@ static void greth_clean_tx_gbit(struct n + greth->tx_free += nr_frags+1; + dev_kfree_skb(skb); + } +- if (greth->tx_free > (MAX_SKB_FRAGS + 1)) { ++ ++ if (netif_queue_stopped(dev) && (greth->tx_free > (MAX_SKB_FRAGS + 1))) { + netif_wake_queue(dev); + } + } + +-static int greth_pending_packets(struct greth_private *greth) +-{ +- struct greth_bd *bdp; +- u32 status; +- bdp = greth->rx_bd_base + greth->rx_cur; +- status = greth_read_bd(&bdp->stat); +- if (status & GRETH_BD_EN) +- return 0; +- else +- return 1; +-} +- + static int greth_rx(struct net_device *dev, int limit) + { + struct greth_private *greth; +@@ -742,20 +741,24 @@ static int greth_rx(struct net_device *d + int pkt_len; + int bad, count; + u32 status, dma_addr; ++ unsigned long flags; + + greth = netdev_priv(dev); + + for (count = 0; count < limit; ++count) { + + bdp = greth->rx_bd_base + greth->rx_cur; ++ GRETH_REGSAVE(greth->regs->status, GRETH_INT_RE | GRETH_INT_RX); ++ mb(); + status = greth_read_bd(&bdp->stat); +- dma_addr = greth_read_bd(&bdp->addr); +- bad = 0; + + if (unlikely(status & GRETH_BD_EN)) { + break; + } + ++ dma_addr = greth_read_bd(&bdp->addr); ++ bad = 0; ++ + /* Check status for errors. */ + if (unlikely(status & GRETH_RXBD_STATUS)) { + if (status & GRETH_RXBD_ERR_FT) { +@@ -817,7 +820,9 @@ static int greth_rx(struct net_device *d + + dma_sync_single_for_device(greth->dev, dma_addr, MAX_FRAME_SIZE, DMA_FROM_DEVICE); + ++ spin_lock_irqsave(&greth->devlock, flags); /* save from XMIT */ + greth_enable_rx(greth); ++ spin_unlock_irqrestore(&greth->devlock, flags); + + greth->rx_cur = NEXT_RX(greth->rx_cur); + } +@@ -851,6 +856,7 @@ static int greth_rx_gbit(struct net_devi + int pkt_len; + int bad, count = 0; + u32 status, dma_addr; ++ unsigned long flags; + + greth = netdev_priv(dev); + +@@ -858,6 +864,8 @@ static int greth_rx_gbit(struct net_devi + + bdp = greth->rx_bd_base + greth->rx_cur; + skb = greth->rx_skbuff[greth->rx_cur]; ++ GRETH_REGSAVE(greth->regs->status, GRETH_INT_RE | GRETH_INT_RX); ++ mb(); + status = greth_read_bd(&bdp->stat); + bad = 0; + +@@ -940,7 +948,9 @@ static int greth_rx_gbit(struct net_devi + + wmb(); + greth_write_bd(&bdp->stat, status); ++ spin_lock_irqsave(&greth->devlock, flags); + greth_enable_rx(greth); ++ spin_unlock_irqrestore(&greth->devlock, flags); + greth->rx_cur = NEXT_RX(greth->rx_cur); + } + +@@ -952,15 +962,19 @@ static int greth_poll(struct napi_struct + { + struct greth_private *greth; + int work_done = 0; ++ unsigned long flags; ++ u32 mask, ctrl; + greth = container_of(napi, struct greth_private, napi); + +- if (greth->gbit_mac) { +- greth_clean_tx_gbit(greth->netdev); +- } else { +- greth_clean_tx(greth->netdev); ++restart_txrx_poll: ++ if ( netif_queue_stopped(greth->netdev) ) { ++ if (greth->gbit_mac) { ++ greth_clean_tx_gbit(greth->netdev); ++ } else { ++ greth_clean_tx(greth->netdev); ++ } + } + +-restart_poll: + if (greth->gbit_mac) { + work_done += greth_rx_gbit(greth->netdev, budget - work_done); + } else { +@@ -969,15 +983,29 @@ restart_poll: + + if (work_done < budget) { + +- napi_complete(napi); ++ spin_lock_irqsave(&greth->devlock, flags); + +- if (greth_pending_packets(greth)) { +- napi_reschedule(napi); +- goto restart_poll; ++ ctrl = GRETH_REGLOAD(greth->regs->control); ++ if (netif_queue_stopped(greth->netdev)) { ++ GRETH_REGSAVE(greth->regs->control, ++ ctrl | GRETH_TXI | GRETH_RXI); ++ mask = GRETH_INT_RX | GRETH_INT_RE | ++ GRETH_INT_TX | GRETH_INT_TE; ++ } else { ++ GRETH_REGSAVE(greth->regs->control, ctrl | GRETH_RXI); ++ mask = GRETH_INT_RX | GRETH_INT_RE; ++ } ++ ++ if (GRETH_REGLOAD(greth->regs->status) & mask) { ++ GRETH_REGSAVE(greth->regs->control, ctrl); ++ spin_unlock_irqrestore(&greth->devlock, flags); ++ goto restart_txrx_poll; ++ } else { ++ __napi_complete(napi); ++ spin_unlock_irqrestore(&greth->devlock, flags); + } + } + +- greth_enable_irqs(greth); + return work_done; + } + +@@ -1172,11 +1200,11 @@ static const struct ethtool_ops greth_et + }; + + static struct net_device_ops greth_netdev_ops = { +- .ndo_open = greth_open, +- .ndo_stop = greth_close, +- .ndo_start_xmit = greth_start_xmit, +- .ndo_set_mac_address = greth_set_mac_add, +- .ndo_validate_addr = eth_validate_addr, ++ .ndo_open = greth_open, ++ .ndo_stop = greth_close, ++ .ndo_start_xmit = greth_start_xmit, ++ .ndo_set_mac_address = greth_set_mac_add, ++ .ndo_validate_addr = eth_validate_addr, + }; + + static inline int wait_for_mdio(struct greth_private *greth) |