mirror of
git://projects.qi-hardware.com/openwrt-xburst.git
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git-svn-id: svn://svn.openwrt.org/openwrt/trunk@25139 3c298f89-4303-0410-b956-a3cf2f4a3e73
400 lines
12 KiB
Diff
400 lines
12 KiB
Diff
From 4439d933884ee3c7e320b8d33bd2e268dd5b6fa5 Mon Sep 17 00:00:00 2001
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From: Daniel Hellstrom <daniel@gaisler.com>
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Date: Wed, 1 Dec 2010 11:40:19 +0100
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Subject: [PATCH] GRETH: resolve SMP issues and other problems
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Fixes the following:
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1. POLL should not enable IRQ when work is not completed
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2. No locking between TX descriptor cleaning and XMIT descriptor handling
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3. No locking between RX POLL and XMIT modifying control register
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4. Since TX cleaning (called from POLL) is running in parallel with XMIT
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unnecessary locking is needed.
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5. IRQ handler looks at RX frame status solely, this is wrong when IRQ is
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temporarily disabled (in POLL), and when IRQ is shared.
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6. IRQ handler clears IRQ status, which is unnecessary
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7. TX queue was stopped in preventing cause when not MAX_SKB_FRAGS+1 descriptors
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were available after a SKB been scheduled by XMIT. Instead the TX queue is
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stopped first when not enough descriptors are available upon entering XMIT.
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It was hard to split up this patch in smaller pieces since all are tied
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together somehow.
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Note the RX flag used in the interrupt handler does not signal that interrtupt
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was asserted, but that a frame was received. Same goes for TX. Also, IRQ is not
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asserted when the RX flag is set before enabling IRQ enable until a new frame is
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received. So extra care must be taken to avoid enabling IRQ and all descriptors
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are already used, hence dead lock will upon us. See new POLL implementation that
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enableds IRQ then look at the RX flag to determine if one or more IRQs may have
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been missed. TX/RX flags are cleared before handling previously enabled
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descriptors, this ensures that the RX/TX flags are valid when determining if IRQ
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should be turned on again.
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By moving TX cleaning from POLL to XMIT in the standard case, removes some
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locking trouble. Enabling TX cleaning from poll only when not enough TX
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descriptors are available is safe because the TX queue is at the same time
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stopped, thus XMIT will not be called. The TX queue is woken up again when
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enough descriptrs are available.
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TX Frames are always enabled with IRQ, however the TX IRQ Enable flag will not
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be enabled until XMIT must wait for free descriptors.
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Locking RX and XMIT parts of the driver from each other is needed because the
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RX/TX enable bits share the same register.
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Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
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---
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drivers/net/greth.c | 158 ++++++++++++++++++++++++++++++---------------------
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1 files changed, 93 insertions(+), 65 deletions(-)
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--- a/drivers/net/greth.c
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+++ b/drivers/net/greth.c
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@@ -1,7 +1,7 @@
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/*
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* Aeroflex Gaisler GRETH 10/100/1G Ethernet MAC.
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*
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- * 2005-2009 (c) Aeroflex Gaisler AB
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+ * 2005-2010 (c) Aeroflex Gaisler AB
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*
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* This driver supports GRETH 10/100 and GRETH 10/100/1G Ethernet MACs
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* available in the GRLIB VHDL IP core library.
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@@ -401,12 +401,20 @@ greth_start_xmit(struct sk_buff *skb, st
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struct greth_private *greth = netdev_priv(dev);
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struct greth_bd *bdp;
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int err = NETDEV_TX_OK;
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- u32 status, dma_addr;
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+ u32 status, dma_addr, ctrl;
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+ unsigned long flags;
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- bdp = greth->tx_bd_base + greth->tx_next;
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+ /* Clean TX Ring */
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+ greth_clean_tx(greth->netdev);
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if (unlikely(greth->tx_free <= 0)) {
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+ spin_lock_irqsave(&greth->devlock, flags); /*save from poll/irq*/
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+ ctrl = GRETH_REGLOAD(greth->regs->control);
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+ /* Enable TX IRQ only if not already in poll() routine */
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+ if ( ctrl & GRETH_RXI )
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+ GRETH_REGSAVE(greth->regs->control, ctrl | GRETH_TXI);
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netif_stop_queue(dev);
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+ spin_unlock_irqrestore(&greth->devlock, flags);
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return NETDEV_TX_BUSY;
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}
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@@ -419,13 +427,14 @@ greth_start_xmit(struct sk_buff *skb, st
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goto out;
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}
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+ bdp = greth->tx_bd_base + greth->tx_next;
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dma_addr = greth_read_bd(&bdp->addr);
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memcpy((unsigned char *) phys_to_virt(dma_addr), skb->data, skb->len);
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dma_sync_single_for_device(greth->dev, dma_addr, skb->len, DMA_TO_DEVICE);
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- status = GRETH_BD_EN | (skb->len & GRETH_BD_LEN);
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+ status = GRETH_BD_EN | GRETH_BD_IE | (skb->len & GRETH_BD_LEN);
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/* Wrap around descriptor ring */
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if (greth->tx_next == GRETH_TXBD_NUM_MASK) {
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@@ -435,22 +444,11 @@ greth_start_xmit(struct sk_buff *skb, st
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greth->tx_next = NEXT_TX(greth->tx_next);
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greth->tx_free--;
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- /* No more descriptors */
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- if (unlikely(greth->tx_free == 0)) {
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-
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- /* Free transmitted descriptors */
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- greth_clean_tx(dev);
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-
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- /* If nothing was cleaned, stop queue & wait for irq */
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- if (unlikely(greth->tx_free == 0)) {
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- status |= GRETH_BD_IE;
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- netif_stop_queue(dev);
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- }
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- }
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-
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/* Write descriptor control word and enable transmission */
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greth_write_bd(&bdp->stat, status);
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+ spin_lock_irqsave(&greth->devlock, flags); /*save from poll/irq*/
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greth_enable_tx(greth);
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+ spin_unlock_irqrestore(&greth->devlock, flags);
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out:
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dev_kfree_skb(skb);
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@@ -463,13 +461,24 @@ greth_start_xmit_gbit(struct sk_buff *sk
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{
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struct greth_private *greth = netdev_priv(dev);
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struct greth_bd *bdp;
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- u32 status = 0, dma_addr;
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+ u32 status = 0, dma_addr, ctrl;
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int curr_tx, nr_frags, i, err = NETDEV_TX_OK;
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+ unsigned long flags;
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nr_frags = skb_shinfo(skb)->nr_frags;
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+ /* Clean TX Ring */
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+ greth_clean_tx_gbit(dev);
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+
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if (greth->tx_free < nr_frags + 1) {
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+ spin_lock_irqsave(&greth->devlock, flags); /*save from poll/irq*/
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+ ctrl = GRETH_REGLOAD(greth->regs->control);
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+ /* Enable TX IRQ only if not already in poll() routine */
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+ if ( ctrl & GRETH_RXI ) {
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+ GRETH_REGSAVE(greth->regs->control, ctrl | GRETH_TXI);
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+ }
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netif_stop_queue(dev);
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+ spin_unlock_irqrestore(&greth->devlock, flags);
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err = NETDEV_TX_BUSY;
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goto out;
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}
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@@ -522,14 +531,8 @@ greth_start_xmit_gbit(struct sk_buff *sk
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/* More fragments left */
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if (i < nr_frags - 1)
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status |= GRETH_TXBD_MORE;
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-
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- /* ... last fragment, check if out of descriptors */
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- else if (greth->tx_free - nr_frags - 1 < (MAX_SKB_FRAGS + 1)) {
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-
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- /* Enable interrupts and stop queue */
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- status |= GRETH_BD_IE;
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- netif_stop_queue(dev);
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- }
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+ else
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+ status |= GRETH_BD_IE; /* enable IRQ on last fragment */
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greth_write_bd(&bdp->stat, status);
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@@ -557,7 +560,9 @@ greth_start_xmit_gbit(struct sk_buff *sk
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wmb();
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+ spin_lock_irqsave(&greth->devlock, flags); /*save from poll/irq*/
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greth_enable_tx(greth);
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+ spin_unlock_irqrestore(&greth->devlock, flags);
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return NETDEV_TX_OK;
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@@ -579,12 +584,11 @@ out:
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return err;
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}
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-
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static irqreturn_t greth_interrupt(int irq, void *dev_id)
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{
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struct net_device *dev = dev_id;
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struct greth_private *greth;
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- u32 status;
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+ u32 status, ctrl;
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irqreturn_t retval = IRQ_NONE;
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greth = netdev_priv(dev);
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@@ -594,13 +598,14 @@ static irqreturn_t greth_interrupt(int i
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/* Get the interrupt events that caused us to be here. */
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status = GRETH_REGLOAD(greth->regs->status);
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- /* Handle rx and tx interrupts through poll */
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- if (status & (GRETH_INT_RE | GRETH_INT_RX | GRETH_INT_TE | GRETH_INT_TX)) {
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+ /* Must see if interrupts are enabled also, INT_TX|INT_RX flags may be set regardless
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+ * of whether IRQ is enabled or not. Especially important when shared IRQ.
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+ */
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+ ctrl = GRETH_REGLOAD(greth->regs->control);
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- /* Clear interrupt status */
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- GRETH_REGSAVE(greth->regs->status,
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- status & (GRETH_INT_RE | GRETH_INT_RX |
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- GRETH_INT_TE | GRETH_INT_TX));
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+ /* Handle rx and tx interrupts through poll */
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+ if (((status & (GRETH_INT_RE | GRETH_INT_RX)) && (ctrl & GRETH_RXI)) ||
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+ ((status & (GRETH_INT_TE | GRETH_INT_TX)) && (ctrl & GRETH_TXI))) {
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retval = IRQ_HANDLED;
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@@ -625,6 +630,8 @@ static void greth_clean_tx(struct net_de
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while (1) {
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bdp = greth->tx_bd_base + greth->tx_last;
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+ GRETH_REGSAVE(greth->regs->status, GRETH_INT_TE | GRETH_INT_TX);
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+ mb();
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stat = greth_read_bd(&bdp->stat);
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if (unlikely(stat & GRETH_BD_EN))
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@@ -685,7 +692,10 @@ static void greth_clean_tx_gbit(struct n
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/* We only clean fully completed SKBs */
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bdp_last_frag = greth->tx_bd_base + SKIP_TX(greth->tx_last, nr_frags);
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- stat = bdp_last_frag->stat;
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+
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+ GRETH_REGSAVE(greth->regs->status, GRETH_INT_TE | GRETH_INT_TX);
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+ mb();
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+ stat = greth_read_bd(&bdp_last_frag->stat);
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if (stat & GRETH_BD_EN)
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break;
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@@ -717,23 +727,12 @@ static void greth_clean_tx_gbit(struct n
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greth->tx_free += nr_frags+1;
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dev_kfree_skb(skb);
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}
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- if (greth->tx_free > (MAX_SKB_FRAGS + 1)) {
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+
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+ if (netif_queue_stopped(dev) && (greth->tx_free > (MAX_SKB_FRAGS + 1))) {
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netif_wake_queue(dev);
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}
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}
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-static int greth_pending_packets(struct greth_private *greth)
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-{
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- struct greth_bd *bdp;
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- u32 status;
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- bdp = greth->rx_bd_base + greth->rx_cur;
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- status = greth_read_bd(&bdp->stat);
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- if (status & GRETH_BD_EN)
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- return 0;
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- else
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- return 1;
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-}
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-
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static int greth_rx(struct net_device *dev, int limit)
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{
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struct greth_private *greth;
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@@ -742,20 +741,24 @@ static int greth_rx(struct net_device *d
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int pkt_len;
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int bad, count;
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u32 status, dma_addr;
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+ unsigned long flags;
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greth = netdev_priv(dev);
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for (count = 0; count < limit; ++count) {
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bdp = greth->rx_bd_base + greth->rx_cur;
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+ GRETH_REGSAVE(greth->regs->status, GRETH_INT_RE | GRETH_INT_RX);
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+ mb();
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status = greth_read_bd(&bdp->stat);
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- dma_addr = greth_read_bd(&bdp->addr);
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- bad = 0;
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if (unlikely(status & GRETH_BD_EN)) {
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break;
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}
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+ dma_addr = greth_read_bd(&bdp->addr);
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+ bad = 0;
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+
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/* Check status for errors. */
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if (unlikely(status & GRETH_RXBD_STATUS)) {
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if (status & GRETH_RXBD_ERR_FT) {
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@@ -817,7 +820,9 @@ static int greth_rx(struct net_device *d
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dma_sync_single_for_device(greth->dev, dma_addr, MAX_FRAME_SIZE, DMA_FROM_DEVICE);
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+ spin_lock_irqsave(&greth->devlock, flags); /* save from XMIT */
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greth_enable_rx(greth);
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+ spin_unlock_irqrestore(&greth->devlock, flags);
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greth->rx_cur = NEXT_RX(greth->rx_cur);
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}
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@@ -851,6 +856,7 @@ static int greth_rx_gbit(struct net_devi
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int pkt_len;
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int bad, count = 0;
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u32 status, dma_addr;
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+ unsigned long flags;
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greth = netdev_priv(dev);
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@@ -858,6 +864,8 @@ static int greth_rx_gbit(struct net_devi
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bdp = greth->rx_bd_base + greth->rx_cur;
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skb = greth->rx_skbuff[greth->rx_cur];
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+ GRETH_REGSAVE(greth->regs->status, GRETH_INT_RE | GRETH_INT_RX);
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+ mb();
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status = greth_read_bd(&bdp->stat);
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bad = 0;
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@@ -940,7 +948,9 @@ static int greth_rx_gbit(struct net_devi
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wmb();
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greth_write_bd(&bdp->stat, status);
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+ spin_lock_irqsave(&greth->devlock, flags);
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greth_enable_rx(greth);
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+ spin_unlock_irqrestore(&greth->devlock, flags);
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greth->rx_cur = NEXT_RX(greth->rx_cur);
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}
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@@ -952,15 +962,19 @@ static int greth_poll(struct napi_struct
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{
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struct greth_private *greth;
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int work_done = 0;
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+ unsigned long flags;
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+ u32 mask, ctrl;
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greth = container_of(napi, struct greth_private, napi);
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- if (greth->gbit_mac) {
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- greth_clean_tx_gbit(greth->netdev);
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- } else {
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- greth_clean_tx(greth->netdev);
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+restart_txrx_poll:
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+ if ( netif_queue_stopped(greth->netdev) ) {
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+ if (greth->gbit_mac) {
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+ greth_clean_tx_gbit(greth->netdev);
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+ } else {
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+ greth_clean_tx(greth->netdev);
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+ }
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}
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-restart_poll:
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if (greth->gbit_mac) {
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work_done += greth_rx_gbit(greth->netdev, budget - work_done);
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} else {
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@@ -969,15 +983,29 @@ restart_poll:
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if (work_done < budget) {
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- napi_complete(napi);
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+ spin_lock_irqsave(&greth->devlock, flags);
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- if (greth_pending_packets(greth)) {
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- napi_reschedule(napi);
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- goto restart_poll;
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+ ctrl = GRETH_REGLOAD(greth->regs->control);
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+ if (netif_queue_stopped(greth->netdev)) {
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+ GRETH_REGSAVE(greth->regs->control,
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+ ctrl | GRETH_TXI | GRETH_RXI);
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+ mask = GRETH_INT_RX | GRETH_INT_RE |
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+ GRETH_INT_TX | GRETH_INT_TE;
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+ } else {
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+ GRETH_REGSAVE(greth->regs->control, ctrl | GRETH_RXI);
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+ mask = GRETH_INT_RX | GRETH_INT_RE;
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+ }
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+
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+ if (GRETH_REGLOAD(greth->regs->status) & mask) {
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+ GRETH_REGSAVE(greth->regs->control, ctrl);
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+ spin_unlock_irqrestore(&greth->devlock, flags);
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+ goto restart_txrx_poll;
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+ } else {
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+ __napi_complete(napi);
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+ spin_unlock_irqrestore(&greth->devlock, flags);
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}
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}
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- greth_enable_irqs(greth);
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return work_done;
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}
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@@ -1172,11 +1200,11 @@ static const struct ethtool_ops greth_et
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};
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static struct net_device_ops greth_netdev_ops = {
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- .ndo_open = greth_open,
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- .ndo_stop = greth_close,
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- .ndo_start_xmit = greth_start_xmit,
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- .ndo_set_mac_address = greth_set_mac_add,
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- .ndo_validate_addr = eth_validate_addr,
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+ .ndo_open = greth_open,
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+ .ndo_stop = greth_close,
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+ .ndo_start_xmit = greth_start_xmit,
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+ .ndo_set_mac_address = greth_set_mac_add,
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+ .ndo_validate_addr = eth_validate_addr,
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};
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static inline int wait_for_mdio(struct greth_private *greth)
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