From: Scott Feldman Date: Wed, 9 Nov 2005 07:18:52 +0000 (-0500) Subject: [netdrvr e100] experiment with doing RX in a similar manner to eepro100 X-Git-Tag: v2.6.22-rc1~1110^2~18 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d52df4a35af569071fda3f4eb08e47cc7023f094;p=linux-2.6 [netdrvr e100] experiment with doing RX in a similar manner to eepro100 I was going to say that eepro100's speedo_rx_link() does the same DMA abuse as e100, but then I noticed one little detail: eepro100 sets both EL (end of list) and S (suspend) bits in the RFD as it chains it to the RFD list. e100 was only setting the EL bit. Hmmm, that's interesting. That means that if HW reads a RFD with the S-bit set, it'll process that RFD and then suspend the receive unit. The receive unit will resume when SW clears the S-bit. There is no need for SW to restart the receive unit. Which means a lot of the receive unit state tracking code in the driver goes away. So here's a patch against 2.6.14. (Sorry for inlining it; the mailer I'm using now will mess with the word wrap). I can't test this on XScale (unless someone has an e100 module for Gumstix :) . It should be doing exactly what eepro100 does with RFDs. I don't believe this change will introduce a performance hit because the S-bit and EL-bit go hand-in-hand meaning if we're going to suspend because of the S- bit, we're on the last resource anyway, so we'll have to wait for SW to replenish. (cherry picked from 29e79da9495261119e3b2e4e7c72507348e75976 commit) --- diff --git a/drivers/net/e100.c b/drivers/net/e100.c index 4d0e0aea72..71c6d334bd 100644 --- a/drivers/net/e100.c +++ b/drivers/net/e100.c @@ -282,12 +282,6 @@ enum scb_status { rus_mask = 0x3C, }; -enum ru_state { - RU_SUSPENDED = 0, - RU_RUNNING = 1, - RU_UNINITIALIZED = -1, -}; - enum scb_stat_ack { stat_ack_not_ours = 0x00, stat_ack_sw_gen = 0x04, @@ -529,7 +523,6 @@ struct nic { struct rx *rx_to_use; struct rx *rx_to_clean; struct rfd blank_rfd; - enum ru_state ru_running; spinlock_t cb_lock ____cacheline_aligned; spinlock_t cmd_lock; @@ -951,7 +944,7 @@ 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 = cpu_to_le16(cb_el & cb_s); nic->blank_rfd.rbd = 0xFFFFFFFF; nic->blank_rfd.size = cpu_to_le16(VLAN_ETH_FRAME_LEN); @@ -1746,19 +1739,11 @@ static int e100_alloc_cbs(struct nic *nic) return 0; } -static inline void e100_start_receiver(struct nic *nic, struct rx *rx) +static inline void e100_start_receiver(struct nic *nic) { - if(!nic->rxs) return; - if(RU_SUSPENDED != nic->ru_running) return; - - /* handle init time starts */ - if(!rx) rx = nic->rxs; - - /* (Re)start RU if suspended or idle and RFA is non-NULL */ - if(rx->skb) { - e100_exec_cmd(nic, ruc_start, rx->dma_addr); - nic->ru_running = RU_RUNNING; - } + /* Start if RFA is non-NULL */ + if(nic->rx_to_clean->skb) + e100_exec_cmd(nic, ruc_start, nic->rx_to_clean->dma_addr); } #define RFD_BUF_LEN (sizeof(struct rfd) + VLAN_ETH_FRAME_LEN) @@ -1787,7 +1772,7 @@ static int e100_rx_alloc_skb(struct nic *nic, struct rx *rx) put_unaligned(cpu_to_le32(rx->dma_addr), (u32 *)&prev_rfd->link); wmb(); - prev_rfd->command &= ~cpu_to_le16(cb_el); + prev_rfd->command &= ~cpu_to_le16(cb_el & cb_s); pci_dma_sync_single_for_device(nic->pdev, rx->prev->dma_addr, sizeof(struct rfd), PCI_DMA_TODEVICE); } @@ -1825,10 +1810,6 @@ 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) - nic->ru_running = RU_SUSPENDED; - /* Pull off the RFD and put the actual data (minus eth hdr) */ skb_reserve(skb, sizeof(struct rfd)); skb_put(skb, actual_size); @@ -1859,45 +1840,18 @@ 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; /* 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; - break; - } else if(-ENODATA == err) + if(e100_rx_indicate(nic, rx, work_done, work_to_do)) 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; - /* Alloc new skbs to refill list */ for(rx = nic->rx_to_use; !rx->skb; rx = nic->rx_to_use = rx->next) { if(unlikely(e100_rx_alloc_skb(nic, rx))) break; /* Better luck next time (see watchdog) */ } - - if(restart_required) { - // ack the rnr? - writeb(stat_ack_rnr, &nic->csr->scb.stat_ack); - e100_start_receiver(nic, rx_to_start); - if(work_done) - (*work_done)++; - } } static void e100_rx_clean_list(struct nic *nic) @@ -1905,8 +1859,6 @@ static void e100_rx_clean_list(struct nic *nic) struct rx *rx; unsigned int i, count = nic->params.rfds.count; - nic->ru_running = RU_UNINITIALIZED; - if(nic->rxs) { for(rx = nic->rxs, i = 0; i < count; rx++, i++) { if(rx->skb) { @@ -1928,7 +1880,6 @@ static int e100_rx_alloc_list(struct nic *nic) unsigned int i, count = nic->params.rfds.count; nic->rx_to_use = nic->rx_to_clean = NULL; - nic->ru_running = RU_UNINITIALIZED; if(!(nic->rxs = kcalloc(count, sizeof(struct rx), GFP_ATOMIC))) return -ENOMEM; @@ -1943,7 +1894,6 @@ static int e100_rx_alloc_list(struct nic *nic) } nic->rx_to_use = nic->rx_to_clean = nic->rxs; - nic->ru_running = RU_SUSPENDED; return 0; } @@ -1963,10 +1913,6 @@ static irqreturn_t e100_intr(int irq, void *dev_id) /* Ack interrupt(s) */ writeb(stat_ack, &nic->csr->scb.stat_ack); - /* We hit Receive No Resource (RNR); restart RU after cleaning */ - if(stat_ack & stat_ack_rnr) - nic->ru_running = RU_SUSPENDED; - if(likely(netif_rx_schedule_prep(netdev))) { e100_disable_irq(nic); __netif_rx_schedule(netdev); @@ -2058,7 +2004,7 @@ static int e100_up(struct nic *nic) if((err = e100_hw_init(nic))) goto err_clean_cbs; e100_set_multicast_list(nic->netdev); - e100_start_receiver(nic, NULL); + e100_start_receiver(nic); mod_timer(&nic->watchdog, jiffies); if((err = request_irq(nic->pdev->irq, e100_intr, IRQF_SHARED, nic->netdev->name, nic->netdev))) @@ -2139,7 +2085,7 @@ static int e100_loopback_test(struct nic *nic, enum loopback loopback_mode) mdio_write(nic->netdev, nic->mii.phy_id, MII_BMCR, BMCR_LOOPBACK); - e100_start_receiver(nic, NULL); + e100_start_receiver(nic); if(!(skb = netdev_alloc_skb(nic->netdev, ETH_DATA_LEN))) { err = -ENOMEM;