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Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/e100.c128
1 files changed, 99 insertions, 29 deletions
diff --git a/drivers/net/e100.c b/drivers/net/e100.c
index 597fd295365..d87636dbdea 100644
--- a/drivers/net/e100.c
+++ b/drivers/net/e100.c
@@ -106,6 +106,13 @@
* the RFD, the RFD must be dma_sync'ed to maintain a consistent
* view from software and hardware.
*
+ * In order to keep updates to the RFD link field from colliding with
+ * hardware writes to mark packets complete, we use the feature that
+ * hardware will not write to a size 0 descriptor and mark the previous
+ * packet as end-of-list (EL). After updating the link, we remove EL
+ * and only then restore the size such that hardware may use the
+ * previous-to-end RFD.
+ *
* Under typical operation, the receive unit (RU) is start once,
* and the controller happily fills RFDs as frames arrive. If
* replacement RFDs cannot be allocated, or the RU goes non-active,
@@ -281,6 +288,7 @@ struct csr {
};
enum scb_status {
+ rus_no_res = 0x08,
rus_ready = 0x10,
rus_mask = 0x3C,
};
@@ -952,7 +960,7 @@ static void e100_get_defaults(struct nic *nic)
((nic->mac >= mac_82558_D101_A4) ? cb_cid : cb_i));
/* Template for a freshly allocated RFD */
- nic->blank_rfd.command = cpu_to_le16(cb_el);
+ nic->blank_rfd.command = 0;
nic->blank_rfd.rbd = 0xFFFFFFFF;
nic->blank_rfd.size = cpu_to_le16(VLAN_ETH_FRAME_LEN);
@@ -1791,15 +1799,12 @@ static int e100_rx_alloc_skb(struct nic *nic, struct rx *rx)
}
/* Link the RFD to end of RFA by linking previous RFD to
- * this one, and clearing EL bit of previous. */
+ * this one. We are safe to touch the previous RFD because
+ * it is protected by the before last buffer's el bit being set */
if(rx->prev->skb) {
struct rfd *prev_rfd = (struct rfd *)rx->prev->skb->data;
put_unaligned(cpu_to_le32(rx->dma_addr),
(u32 *)&prev_rfd->link);
- wmb();
- prev_rfd->command &= ~cpu_to_le16(cb_el);
- pci_dma_sync_single_for_device(nic->pdev, rx->prev->dma_addr,
- sizeof(struct rfd), PCI_DMA_TODEVICE);
}
return 0;
@@ -1824,8 +1829,19 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
DPRINTK(RX_STATUS, DEBUG, "status=0x%04X\n", rfd_status);
/* If data isn't ready, nothing to indicate */
- if(unlikely(!(rfd_status & cb_complete)))
+ if (unlikely(!(rfd_status & cb_complete))) {
+ /* If the next buffer has the el bit, but we think the receiver
+ * is still running, check to see if it really stopped while
+ * we had interrupts off.
+ * This allows for a fast restart without re-enabling
+ * interrupts */
+ if ((le16_to_cpu(rfd->command) & cb_el) &&
+ (RU_RUNNING == nic->ru_running))
+
+ if (readb(&nic->csr->scb.status) & rus_no_res)
+ nic->ru_running = RU_SUSPENDED;
return -ENODATA;
+ }
/* Get actual data size */
actual_size = le16_to_cpu(rfd->actual_size) & 0x3FFF;
@@ -1836,9 +1852,18 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
pci_unmap_single(nic->pdev, rx->dma_addr,
RFD_BUF_LEN, PCI_DMA_FROMDEVICE);
- /* this allows for a fast restart without re-enabling interrupts */
- if(le16_to_cpu(rfd->command) & cb_el)
+ /* If this buffer has the el bit, but we think the receiver
+ * is still running, check to see if it really stopped while
+ * we had interrupts off.
+ * This allows for a fast restart without re-enabling interrupts.
+ * This can happen when the RU sees the size change but also sees
+ * the el bit set. */
+ if ((le16_to_cpu(rfd->command) & cb_el) &&
+ (RU_RUNNING == nic->ru_running)) {
+
+ if (readb(&nic->csr->scb.status) & rus_no_res)
nic->ru_running = RU_SUSPENDED;
+ }
/* Pull off the RFD and put the actual data (minus eth hdr) */
skb_reserve(skb, sizeof(struct rfd));
@@ -1870,31 +1895,30 @@ static void e100_rx_clean(struct nic *nic, unsigned int *work_done,
unsigned int work_to_do)
{
struct rx *rx;
- int restart_required = 0;
- struct rx *rx_to_start = NULL;
-
- /* are we already rnr? then pay attention!!! this ensures that
- * the state machine progression never allows a start with a
- * partially cleaned list, avoiding a race between hardware
- * and rx_to_clean when in NAPI mode */
- if(RU_SUSPENDED == nic->ru_running)
- restart_required = 1;
+ int restart_required = 0, err = 0;
+ struct rx *old_before_last_rx, *new_before_last_rx;
+ struct rfd *old_before_last_rfd, *new_before_last_rfd;
/* Indicate newly arrived packets */
for(rx = nic->rx_to_clean; rx->skb; rx = nic->rx_to_clean = rx->next) {
- int err = e100_rx_indicate(nic, rx, work_done, work_to_do);
- if(-EAGAIN == err) {
- /* hit quota so have more work to do, restart once
- * cleanup is complete */
- restart_required = 0;
+ err = e100_rx_indicate(nic, rx, work_done, work_to_do);
+ /* Hit quota or no more to clean */
+ if (-EAGAIN == err || -ENODATA == err)
break;
- } else if(-ENODATA == err)
- break; /* No more to clean */
}
- /* save our starting point as the place we'll restart the receiver */
- if(restart_required)
- rx_to_start = nic->rx_to_clean;
+
+ /* On EAGAIN, hit quota so have more work to do, restart once
+ * cleanup is complete.
+ * Else, are we already rnr? then pay attention!!! this ensures that
+ * the state machine progression never allows a start with a
+ * partially cleaned list, avoiding a race between hardware
+ * and rx_to_clean when in NAPI mode */
+ if (-EAGAIN != err && RU_SUSPENDED == nic->ru_running)
+ restart_required = 1;
+
+ old_before_last_rx = nic->rx_to_use->prev->prev;
+ old_before_last_rfd = (struct rfd *)old_before_last_rx->skb->data;
/* Alloc new skbs to refill list */
for(rx = nic->rx_to_use; !rx->skb; rx = nic->rx_to_use = rx->next) {
@@ -1902,10 +1926,42 @@ static void e100_rx_clean(struct nic *nic, unsigned int *work_done,
break; /* Better luck next time (see watchdog) */
}
+ new_before_last_rx = nic->rx_to_use->prev->prev;
+ if (new_before_last_rx != old_before_last_rx) {
+ /* Set the el-bit on the buffer that is before the last buffer.
+ * This lets us update the next pointer on the last buffer
+ * without worrying about hardware touching it.
+ * We set the size to 0 to prevent hardware from touching this
+ * buffer.
+ * When the hardware hits the before last buffer with el-bit
+ * and size of 0, it will RNR interrupt, the RUS will go into
+ * the No Resources state. It will not complete nor write to
+ * this buffer. */
+ new_before_last_rfd =
+ (struct rfd *)new_before_last_rx->skb->data;
+ new_before_last_rfd->size = 0;
+ new_before_last_rfd->command |= cpu_to_le16(cb_el);
+ pci_dma_sync_single_for_device(nic->pdev,
+ new_before_last_rx->dma_addr, sizeof(struct rfd),
+ PCI_DMA_TODEVICE);
+
+ /* Now that we have a new stopping point, we can clear the old
+ * stopping point. We must sync twice to get the proper
+ * ordering on the hardware side of things. */
+ old_before_last_rfd->command &= ~cpu_to_le16(cb_el);
+ pci_dma_sync_single_for_device(nic->pdev,
+ old_before_last_rx->dma_addr, sizeof(struct rfd),
+ PCI_DMA_TODEVICE);
+ old_before_last_rfd->size = cpu_to_le16(VLAN_ETH_FRAME_LEN);
+ pci_dma_sync_single_for_device(nic->pdev,
+ old_before_last_rx->dma_addr, sizeof(struct rfd),
+ PCI_DMA_TODEVICE);
+ }
+
if(restart_required) {
// ack the rnr?
writeb(stat_ack_rnr, &nic->csr->scb.stat_ack);
- e100_start_receiver(nic, rx_to_start);
+ e100_start_receiver(nic, nic->rx_to_clean);
if(work_done)
(*work_done)++;
}
@@ -1937,6 +1993,7 @@ static int e100_rx_alloc_list(struct nic *nic)
{
struct rx *rx;
unsigned int i, count = nic->params.rfds.count;
+ struct rfd *before_last;
nic->rx_to_use = nic->rx_to_clean = NULL;
nic->ru_running = RU_UNINITIALIZED;
@@ -1952,6 +2009,19 @@ static int e100_rx_alloc_list(struct nic *nic)
return -ENOMEM;
}
}
+ /* Set the el-bit on the buffer that is before the last buffer.
+ * This lets us update the next pointer on the last buffer without
+ * worrying about hardware touching it.
+ * We set the size to 0 to prevent hardware from touching this buffer.
+ * When the hardware hits the before last buffer with el-bit and size
+ * of 0, it will RNR interrupt, the RU will go into the No Resources
+ * state. It will not complete nor write to this buffer. */
+ rx = nic->rxs->prev->prev;
+ before_last = (struct rfd *)rx->skb->data;
+ before_last->command |= cpu_to_le16(cb_el);
+ before_last->size = 0;
+ pci_dma_sync_single_for_device(nic->pdev, rx->dma_addr,
+ sizeof(struct rfd), PCI_DMA_TODEVICE);
nic->rx_to_use = nic->rx_to_clean = nic->rxs;
nic->ru_running = RU_SUSPENDED;
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-02 22:30:23 +0000