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Date: Fri, 23 Nov 2012 14:50:01 +0100
From: Nicolas Ferre <nicolas.ferre@...el.com>
To: "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>
CC: <linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>,
Joachim Eastwood <manabian@...il.com>,
Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
Havard Skinnemoen <havard@...nnemoen.net>,
Nicolas Ferre <nicolas.ferre@...el.com>
Subject: [PATCH] net/macb: Use non-coherent memory for rx buffers
From: Havard Skinnemoen <havard@...nnemoen.net>
Allocate regular pages to use as backing for the RX ring and use the
DMA API to sync the caches. This should give a bit better performance
since it allows the CPU to do burst transfers from memory. It is also
a necessary step on the way to reduce the amount of copying done by
the driver.
Signed-off-by: Havard Skinnemoen <havard@...nnemoen.net>
[nicolas.ferre@...el.com: adapt to newer kernel]
Signed-off-by: Nicolas Ferre <nicolas.ferre@...el.com>
---
drivers/net/ethernet/cadence/macb.c | 206 +++++++++++++++++++++++-------------
drivers/net/ethernet/cadence/macb.h | 20 +++-
2 files changed, 148 insertions(+), 78 deletions(-)
diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index 6a59bce..c2955da 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -10,6 +10,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/clk.h>
+#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
@@ -35,6 +36,8 @@
#define RX_BUFFER_SIZE 128
#define RX_RING_SIZE 512 /* must be power of 2 */
#define RX_RING_BYTES (sizeof(struct macb_dma_desc) * RX_RING_SIZE)
+#define RX_BUFFERS_PER_PAGE (PAGE_SIZE / RX_BUFFER_SIZE)
+#define RX_RING_PAGES (RX_RING_SIZE / RX_BUFFERS_PER_PAGE)
#define TX_RING_SIZE 128 /* must be power of 2 */
#define TX_RING_BYTES (sizeof(struct macb_dma_desc) * TX_RING_SIZE)
@@ -90,9 +93,16 @@ static struct macb_dma_desc *macb_rx_desc(struct macb *bp, unsigned int index)
return &bp->rx_ring[macb_rx_ring_wrap(index)];
}
-static void *macb_rx_buffer(struct macb *bp, unsigned int index)
+static struct macb_rx_page *macb_rx_page(struct macb *bp, unsigned int index)
{
- return bp->rx_buffers + RX_BUFFER_SIZE * macb_rx_ring_wrap(index);
+ unsigned int entry = macb_rx_ring_wrap(index);
+
+ return &bp->rx_page[entry / RX_BUFFERS_PER_PAGE];
+}
+
+static unsigned int macb_rx_page_offset(struct macb *bp, unsigned int index)
+{
+ return (index % RX_BUFFERS_PER_PAGE) * RX_BUFFER_SIZE;
}
void macb_set_hwaddr(struct macb *bp)
@@ -528,11 +538,15 @@ static void macb_tx_interrupt(struct macb *bp)
static int macb_rx_frame(struct macb *bp, unsigned int first_frag,
unsigned int last_frag)
{
- unsigned int len;
- unsigned int frag;
- unsigned int offset;
- struct sk_buff *skb;
- struct macb_dma_desc *desc;
+ unsigned int len;
+ unsigned int frag;
+ unsigned int skb_offset;
+ unsigned int pg_offset;
+ struct macb_rx_page *rx_page;
+ dma_addr_t phys;
+ void *buf;
+ struct sk_buff *skb;
+ struct macb_dma_desc *desc;
desc = macb_rx_desc(bp, last_frag);
len = MACB_BFEXT(RX_FRMLEN, desc->ctrl);
@@ -566,7 +580,7 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag,
return 1;
}
- offset = 0;
+ skb_offset = 0;
len += NET_IP_ALIGN;
skb_checksum_none_assert(skb);
skb_put(skb, len);
@@ -574,13 +588,28 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag,
for (frag = first_frag; ; frag++) {
unsigned int frag_len = RX_BUFFER_SIZE;
- if (offset + frag_len > len) {
+ if (skb_offset + frag_len > len) {
BUG_ON(frag != last_frag);
- frag_len = len - offset;
+ frag_len = len - skb_offset;
}
- skb_copy_to_linear_data_offset(skb, offset,
- macb_rx_buffer(bp, frag), frag_len);
- offset += RX_BUFFER_SIZE;
+
+ rx_page = macb_rx_page(bp, frag);
+ pg_offset = macb_rx_page_offset(bp, frag);
+ phys = rx_page->phys;
+
+ dma_sync_single_range_for_cpu(&bp->pdev->dev, phys,
+ pg_offset, frag_len, DMA_FROM_DEVICE);
+
+ buf = kmap_atomic(rx_page->page);
+ skb_copy_to_linear_data_offset(skb, skb_offset,
+ buf + pg_offset, frag_len);
+ kunmap_atomic(buf);
+
+ skb_offset += frag_len;
+
+ dma_sync_single_range_for_device(&bp->pdev->dev, phys,
+ pg_offset, frag_len, DMA_FROM_DEVICE);
+
desc = macb_rx_desc(bp, frag);
desc->addr &= ~MACB_BIT(RX_USED);
@@ -860,86 +889,90 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
return NETDEV_TX_OK;
}
-static void macb_free_consistent(struct macb *bp)
+static void macb_free_rings(struct macb *bp)
{
- if (bp->tx_skb) {
- kfree(bp->tx_skb);
- bp->tx_skb = NULL;
- }
- if (bp->rx_ring) {
- dma_free_coherent(&bp->pdev->dev, RX_RING_BYTES,
- bp->rx_ring, bp->rx_ring_dma);
- bp->rx_ring = NULL;
- }
- if (bp->tx_ring) {
- dma_free_coherent(&bp->pdev->dev, TX_RING_BYTES,
- bp->tx_ring, bp->tx_ring_dma);
- bp->tx_ring = NULL;
- }
- if (bp->rx_buffers) {
- dma_free_coherent(&bp->pdev->dev,
- RX_RING_SIZE * RX_BUFFER_SIZE,
- bp->rx_buffers, bp->rx_buffers_dma);
- bp->rx_buffers = NULL;
+ int i;
+
+ for (i = 0; i < RX_RING_PAGES; i++) {
+ struct macb_rx_page *rx_page = &bp->rx_page[i];
+
+ if (!rx_page->page)
+ continue;
+
+ dma_unmap_page(&bp->pdev->dev, rx_page->phys,
+ PAGE_SIZE, DMA_FROM_DEVICE);
+ put_page(rx_page->page);
+ rx_page->page = NULL;
}
+
+ kfree(bp->tx_skb);
+ kfree(bp->rx_page);
+ dma_free_coherent(&bp->pdev->dev, TX_RING_BYTES, bp->tx_ring,
+ bp->tx_ring_dma);
+ dma_free_coherent(&bp->pdev->dev, RX_RING_BYTES, bp->rx_ring,
+ bp->rx_ring_dma);
}
-static int macb_alloc_consistent(struct macb *bp)
+static int macb_init_rings(struct macb *bp)
{
- int size;
+ struct page *page;
+ dma_addr_t phys;
+ unsigned int page_idx;
+ unsigned int ring_idx;
+ unsigned int i;
- size = TX_RING_SIZE * sizeof(struct macb_tx_skb);
- bp->tx_skb = kmalloc(size, GFP_KERNEL);
- if (!bp->tx_skb)
- goto out_err;
-
- size = RX_RING_BYTES;
- bp->rx_ring = dma_alloc_coherent(&bp->pdev->dev, size,
+ bp->rx_ring = dma_alloc_coherent(&bp->pdev->dev, RX_RING_BYTES,
&bp->rx_ring_dma, GFP_KERNEL);
if (!bp->rx_ring)
- goto out_err;
+ goto err_alloc_rx_ring;
+
netdev_dbg(bp->dev,
"Allocated RX ring of %d bytes at %08lx (mapped %p)\n",
- size, (unsigned long)bp->rx_ring_dma, bp->rx_ring);
+ RX_RING_BYTES, (unsigned long)bp->rx_ring_dma, bp->rx_ring);
- size = TX_RING_BYTES;
- bp->tx_ring = dma_alloc_coherent(&bp->pdev->dev, size,
+ bp->tx_ring = dma_alloc_coherent(&bp->pdev->dev, TX_RING_BYTES,
&bp->tx_ring_dma, GFP_KERNEL);
if (!bp->tx_ring)
- goto out_err;
- netdev_dbg(bp->dev,
- "Allocated TX ring of %d bytes at %08lx (mapped %p)\n",
- size, (unsigned long)bp->tx_ring_dma, bp->tx_ring);
-
- size = RX_RING_SIZE * RX_BUFFER_SIZE;
- bp->rx_buffers = dma_alloc_coherent(&bp->pdev->dev, size,
- &bp->rx_buffers_dma, GFP_KERNEL);
- if (!bp->rx_buffers)
- goto out_err;
+ goto err_alloc_tx_ring;
+
netdev_dbg(bp->dev,
- "Allocated RX buffers of %d bytes at %08lx (mapped %p)\n",
- size, (unsigned long)bp->rx_buffers_dma, bp->rx_buffers);
+ "Allocated TX ring of %d bytes at 0x%08lx (mapped %p)\n",
+ TX_RING_BYTES, (unsigned long)bp->tx_ring_dma, bp->tx_ring);
- return 0;
+ bp->rx_page = kcalloc(RX_RING_PAGES, sizeof(struct macb_rx_page),
+ GFP_KERNEL);
+ if (!bp->rx_page)
+ goto err_alloc_rx_page;
-out_err:
- macb_free_consistent(bp);
- return -ENOMEM;
-}
+ bp->tx_skb = kcalloc(TX_RING_SIZE, sizeof(struct macb_tx_skb),
+ GFP_KERNEL);
+ if (!bp->tx_skb)
+ goto err_alloc_tx_skb;
-static void macb_init_rings(struct macb *bp)
-{
- int i;
- dma_addr_t addr;
+ for (page_idx = 0, ring_idx = 0; page_idx < RX_RING_PAGES; page_idx++) {
+ page = alloc_page(GFP_KERNEL);
+ if (!page)
+ goto err_alloc_page;
+
+ phys = dma_map_page(&bp->pdev->dev, page, 0, PAGE_SIZE,
+ DMA_FROM_DEVICE);
+ if (dma_mapping_error(&bp->pdev->dev, phys))
+ goto err_map_page;
+
+ bp->rx_page[page_idx].page = page;
+ bp->rx_page[page_idx].phys = phys;
- addr = bp->rx_buffers_dma;
- for (i = 0; i < RX_RING_SIZE; i++) {
- bp->rx_ring[i].addr = addr;
- bp->rx_ring[i].ctrl = 0;
- addr += RX_BUFFER_SIZE;
+ for (i = 0; i < RX_BUFFERS_PER_PAGE; i++, ring_idx++) {
+ bp->rx_ring[ring_idx].addr = phys;
+ bp->rx_ring[ring_idx].ctrl = 0;
+ phys += RX_BUFFER_SIZE;
+ }
}
bp->rx_ring[RX_RING_SIZE - 1].addr |= MACB_BIT(RX_WRAP);
+ netdev_dbg(bp->dev, "Allocated %u RX buffers (%lu pages)\n",
+ RX_RING_SIZE, RX_RING_PAGES);
+
for (i = 0; i < TX_RING_SIZE; i++) {
bp->tx_ring[i].addr = 0;
bp->tx_ring[i].ctrl = MACB_BIT(TX_USED);
@@ -947,6 +980,28 @@ static void macb_init_rings(struct macb *bp)
bp->tx_ring[TX_RING_SIZE - 1].ctrl |= MACB_BIT(TX_WRAP);
bp->rx_tail = bp->tx_head = bp->tx_tail = 0;
+
+ return 0;
+
+err_map_page:
+ __free_page(page);
+err_alloc_page:
+ while (page_idx--) {
+ dma_unmap_page(&bp->pdev->dev, bp->rx_page[page_idx].phys,
+ PAGE_SIZE, DMA_FROM_DEVICE);
+ __free_page(bp->rx_page[page_idx].page);
+ }
+ kfree(bp->tx_skb);
+err_alloc_tx_skb:
+ kfree(bp->rx_page);
+err_alloc_rx_page:
+ dma_free_coherent(&bp->pdev->dev, TX_RING_BYTES, bp->tx_ring,
+ bp->tx_ring_dma);
+err_alloc_tx_ring:
+ dma_free_coherent(&bp->pdev->dev, RX_RING_BYTES, bp->rx_ring,
+ bp->rx_ring_dma);
+err_alloc_rx_ring:
+ return -ENOMEM;
}
static void macb_reset_hw(struct macb *bp)
@@ -1221,16 +1276,15 @@ static int macb_open(struct net_device *dev)
if (!bp->phy_dev)
return -EAGAIN;
- err = macb_alloc_consistent(bp);
+ err = macb_init_rings(bp);
if (err) {
- netdev_err(dev, "Unable to allocate DMA memory (error %d)\n",
+ netdev_err(dev, "Unable to allocate DMA rings (error %d)\n",
err);
return err;
}
napi_enable(&bp->napi);
- macb_init_rings(bp);
macb_init_hw(bp);
/* schedule a link state check */
@@ -1257,7 +1311,7 @@ static int macb_close(struct net_device *dev)
netif_carrier_off(dev);
spin_unlock_irqrestore(&bp->lock, flags);
- macb_free_consistent(bp);
+ macb_free_rings(bp);
return 0;
}
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 570908b..74e68a3 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -453,6 +453,23 @@ struct macb_dma_desc {
#define MACB_TX_USED_SIZE 1
/**
+ * struct macb_rx_page - data associated with a page used as RX buffers
+ * @page: Physical page used as storage for the buffers
+ * @phys: DMA address of the page
+ *
+ * Each page is used to provide %MACB_RX_BUFFERS_PER_PAGE RX buffers.
+ * The page gets an initial reference when it is inserted into the
+ * ring, and an additional reference each time it is passed up the
+ * stack as a fragment. When all the buffers have been used, we drop
+ * the initial reference and allocate a new page. Any additional
+ * references are dropped when the higher layers free the skb.
+ */
+struct macb_rx_page {
+ struct page *page;
+ dma_addr_t phys;
+};
+
+/**
* struct macb_tx_skb - data about an skb which is being transmitted
* @skb: skb currently being transmitted
* @mapping: DMA address of the skb's data buffer
@@ -543,7 +560,7 @@ struct macb {
unsigned int rx_tail;
struct macb_dma_desc *rx_ring;
- void *rx_buffers;
+ struct macb_rx_page *rx_page;
unsigned int tx_head, tx_tail;
struct macb_dma_desc *tx_ring;
@@ -564,7 +581,6 @@ struct macb {
dma_addr_t rx_ring_dma;
dma_addr_t tx_ring_dma;
- dma_addr_t rx_buffers_dma;
struct mii_bus *mii_bus;
struct phy_device *phy_dev;
--
1.8.0
--
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