126 lines
3.7 KiB
Diff
126 lines
3.7 KiB
Diff
From: Felix Fietkau <nbd@nbd.name>
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Date: Sun, 12 Apr 2015 09:58:56 +0200
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Subject: [PATCH] bgmac: simplify tx ring index handling
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Keep incrementing ring->start and ring->end instead of pointing it to
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the actual ring slot entry. This simplifies the calculation of the
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number of free slots.
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Signed-off-by: Felix Fietkau <nbd@nbd.name>
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---
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--- a/drivers/net/ethernet/broadcom/bgmac.c
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+++ b/drivers/net/ethernet/broadcom/bgmac.c
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@@ -142,11 +142,10 @@ static netdev_tx_t bgmac_dma_tx_add(stru
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{
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struct device *dma_dev = bgmac->core->dma_dev;
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struct net_device *net_dev = bgmac->net_dev;
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- struct bgmac_slot_info *slot = &ring->slots[ring->end];
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- int free_slots;
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+ int index = ring->end % BGMAC_TX_RING_SLOTS;
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+ struct bgmac_slot_info *slot = &ring->slots[index];
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int nr_frags;
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u32 flags;
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- int index = ring->end;
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int i;
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if (skb->len > BGMAC_DESC_CTL1_LEN) {
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@@ -159,12 +158,10 @@ static netdev_tx_t bgmac_dma_tx_add(stru
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nr_frags = skb_shinfo(skb)->nr_frags;
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- if (ring->start <= ring->end)
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- free_slots = ring->start - ring->end + BGMAC_TX_RING_SLOTS;
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- else
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- free_slots = ring->start - ring->end;
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-
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- if (free_slots <= nr_frags + 1) {
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+ /* ring->end - ring->start will return the number of valid slots,
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+ * even when ring->end overflows
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+ */
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+ if (ring->end - ring->start + nr_frags + 1 >= BGMAC_TX_RING_SLOTS) {
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bgmac_err(bgmac, "TX ring is full, queue should be stopped!\n");
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netif_stop_queue(net_dev);
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return NETDEV_TX_BUSY;
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@@ -200,7 +197,7 @@ static netdev_tx_t bgmac_dma_tx_add(stru
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}
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slot->skb = skb;
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-
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+ ring->end += nr_frags + 1;
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netdev_sent_queue(net_dev, skb->len);
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wmb();
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@@ -208,13 +205,12 @@ static netdev_tx_t bgmac_dma_tx_add(stru
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/* Increase ring->end to point empty slot. We tell hardware the first
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* slot it should *not* read.
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*/
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- ring->end = (index + 1) % BGMAC_TX_RING_SLOTS;
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bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_INDEX,
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ring->index_base +
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- ring->end * sizeof(struct bgmac_dma_desc));
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+ (ring->end % BGMAC_TX_RING_SLOTS) *
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+ sizeof(struct bgmac_dma_desc));
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- free_slots -= nr_frags + 1;
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- if (free_slots < 8)
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+ if (ring->end - ring->start >= BGMAC_TX_RING_SLOTS - 8)
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netif_stop_queue(net_dev);
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return NETDEV_TX_OK;
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@@ -256,17 +252,17 @@ static void bgmac_dma_tx_free(struct bgm
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empty_slot &= BGMAC_DMA_TX_STATDPTR;
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empty_slot /= sizeof(struct bgmac_dma_desc);
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- while (ring->start != empty_slot) {
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- struct bgmac_slot_info *slot = &ring->slots[ring->start];
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- u32 ctl1 = le32_to_cpu(ring->cpu_base[ring->start].ctl1);
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- int len = ctl1 & BGMAC_DESC_CTL1_LEN;
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+ while (ring->start != ring->end) {
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+ int slot_idx = ring->start % BGMAC_TX_RING_SLOTS;
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+ struct bgmac_slot_info *slot = &ring->slots[slot_idx];
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+ u32 ctl1;
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+ int len;
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- if (!slot->dma_addr) {
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- bgmac_err(bgmac, "Hardware reported transmission for empty TX ring slot %d! End of ring: %d\n",
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- ring->start, ring->end);
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- goto next;
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- }
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+ if (slot_idx == empty_slot)
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+ break;
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+ ctl1 = le32_to_cpu(ring->cpu_base[slot_idx].ctl1);
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+ len = ctl1 & BGMAC_DESC_CTL1_LEN;
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if (ctl1 & BGMAC_DESC_CTL0_SOF)
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/* Unmap no longer used buffer */
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dma_unmap_single(dma_dev, slot->dma_addr, len,
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@@ -284,10 +280,8 @@ static void bgmac_dma_tx_free(struct bgm
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slot->skb = NULL;
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}
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-next:
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slot->dma_addr = 0;
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- if (++ring->start >= BGMAC_TX_RING_SLOTS)
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- ring->start = 0;
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+ ring->start++;
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freed = true;
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}
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--- a/drivers/net/ethernet/broadcom/bgmac.h
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+++ b/drivers/net/ethernet/broadcom/bgmac.h
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@@ -414,10 +414,10 @@ enum bgmac_dma_ring_type {
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* empty.
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*/
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struct bgmac_dma_ring {
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- u16 num_slots;
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- u16 start;
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- u16 end;
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+ u32 start;
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+ u32 end;
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+ u16 num_slots;
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u16 mmio_base;
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struct bgmac_dma_desc *cpu_base;
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dma_addr_t dma_base;
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