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Commit b38c83dd authored by Felix Fietkau's avatar Felix Fietkau Committed by David S. Miller
Browse files

bgmac: simplify tx ring index handling 



Keep incrementing ring->start and ring->end instead of pointing it to
the actual ring slot entry. This simplifies the calculation of the
number of free slots.

Signed-off-by: default avatarFelix Fietkau <nbd@openwrt.org>
Acked-by: default avatarRafał Miłecki <zajec5@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e0767834

drivers/net/ethernet/broadcom/bgmac.c

+20 −26
Original line number Diff line number Diff line
@@ -142,11 +142,10 @@ static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac, 
{

	struct device *dma_dev = bgmac->core->dma_dev;

	struct net_device *net_dev = bgmac->net_dev;

	struct bgmac_slot_info *slot = &ring->slots[ring->end];

	int free_slots;

	int index = ring->end % BGMAC_TX_RING_SLOTS;

	struct bgmac_slot_info *slot = &ring->slots[index];

	int nr_frags;

	u32 flags;

	int index = ring->end;

	int i;



	if (skb->len > BGMAC_DESC_CTL1_LEN) {
@@ -159,12 +158,10 @@ static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac, 


	nr_frags = skb_shinfo(skb)->nr_frags;



	if (ring->start <= ring->end)

		free_slots = ring->start - ring->end + BGMAC_TX_RING_SLOTS;

	else

		free_slots = ring->start - ring->end;



	if (free_slots <= nr_frags + 1) {

	/* ring->end - ring->start will return the number of valid slots,

	 * even when ring->end overflows

	 */

	if (ring->end - ring->start + nr_frags + 1 >= BGMAC_TX_RING_SLOTS) {

		bgmac_err(bgmac, "TX ring is full, queue should be stopped!\n");

		netif_stop_queue(net_dev);

		return NETDEV_TX_BUSY;
@@ -200,7 +197,7 @@ static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac, 
	}



	slot->skb = skb;



	ring->end += nr_frags + 1;

	netdev_sent_queue(net_dev, skb->len);



	wmb();
@@ -208,13 +205,12 @@ static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac, 
	/* Increase ring->end to point empty slot. We tell hardware the first

	 * slot it should *not* read.

	 */

	ring->end = (index + 1) % BGMAC_TX_RING_SLOTS;

	bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_INDEX,

		    ring->index_base +

		    ring->end * sizeof(struct bgmac_dma_desc));

		    (ring->end % BGMAC_TX_RING_SLOTS) *

		    sizeof(struct bgmac_dma_desc));



	free_slots -= nr_frags + 1;

	if (free_slots < 8)

	if (ring->end - ring->start >= BGMAC_TX_RING_SLOTS - 8)

		netif_stop_queue(net_dev);



	return NETDEV_TX_OK;
@@ -256,17 +252,17 @@ static void bgmac_dma_tx_free(struct bgmac *bgmac, struct bgmac_dma_ring *ring) 
	empty_slot &= BGMAC_DMA_TX_STATDPTR;

	empty_slot /= sizeof(struct bgmac_dma_desc);



	while (ring->start != empty_slot) {

		struct bgmac_slot_info *slot = &ring->slots[ring->start];

		u32 ctl1 = le32_to_cpu(ring->cpu_base[ring->start].ctl1);

		int len = ctl1 & BGMAC_DESC_CTL1_LEN;

	while (ring->start != ring->end) {

		int slot_idx = ring->start % BGMAC_TX_RING_SLOTS;

		struct bgmac_slot_info *slot = &ring->slots[slot_idx];

		u32 ctl1;

		int len;



		if (!slot->dma_addr) {

			bgmac_err(bgmac, "Hardware reported transmission for empty TX ring slot %d! End of ring: %d\n",

				  ring->start, ring->end);

			goto next;

		}

		if (slot_idx == empty_slot)

			break;



		ctl1 = le32_to_cpu(ring->cpu_base[slot_idx].ctl1);

		len = ctl1 & BGMAC_DESC_CTL1_LEN;

		if (ctl1 & BGMAC_DESC_CTL0_SOF)

			/* Unmap no longer used buffer */

			dma_unmap_single(dma_dev, slot->dma_addr, len,
@@ -284,10 +280,8 @@ static void bgmac_dma_tx_free(struct bgmac *bgmac, struct bgmac_dma_ring *ring) 
			slot->skb = NULL;

		}



next:

		slot->dma_addr = 0;

		if (++ring->start >= BGMAC_TX_RING_SLOTS)

			ring->start = 0;

		ring->start++;

		freed = true;

	}

drivers/net/ethernet/broadcom/bgmac.h

+3 −3
Original line number Diff line number Diff line
@@ -414,10 +414,10 @@ enum bgmac_dma_ring_type { 
 * empty.

 */

struct bgmac_dma_ring {

	u16 num_slots;

	u16 start;

	u16 end;

	u32 start;

	u32 end;



	u16 num_slots;

	u16 mmio_base;

	struct bgmac_dma_desc *cpu_base;

	dma_addr_t dma_base;