diff options
| -rw-r--r-- | drivers/net/e100.c | 128 |
1 files changed, 99 insertions, 29 deletions
diff --git a/drivers/net/e100.c b/drivers/net/e100.c index 597fd29..d87636d 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; |
