[PATCH] net/macb: increase RX buffer size for GEM
From: Nicolas Ferre
Date: Mon Dec 03 2012 - 07:15:39 EST
Macb Ethernet controller requires a RX buffer of 128 bytes. It is
highly sub-optimal for Gigabit-capable GEM that is able to use
a bigger DMA buffer. Change this constant and associated macros
with data stored in the private structure.
I also kept the result of buffers per page calculation to lower the
impact of this move to a variable rx buffer size on rx hot path.
RX DMA buffer size has to be multiple of 64 bytes as indicated in
DMA Configuration Register specification.
Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
---
drivers/net/ethernet/cadence/macb.c | 61 ++++++++++++++++++++++++++++---------
drivers/net/ethernet/cadence/macb.h | 2 ++
2 files changed, 49 insertions(+), 14 deletions(-)
diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index 4b541a3..b4f45f4 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -34,11 +34,11 @@
#include "macb.h"
-#define RX_BUFFER_SIZE 128
+#define MACB_RX_BUFFER_SIZE 128
+#define GEM_RX_BUFFER_SIZE 2048
+#define RX_BUFFER_MULTIPLE 64 /* bytes */
#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)
@@ -98,12 +98,17 @@ static struct macb_rx_page *macb_rx_page(struct macb *bp, unsigned int index)
{
unsigned int entry = macb_rx_ring_wrap(index);
- return &bp->rx_page[entry / RX_BUFFERS_PER_PAGE];
+ return &bp->rx_page[entry / bp->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;
+ return (index % bp->rx_buffers_per_page) * bp->rx_buffer_size;
+}
+
+static unsigned int rx_ring_pages(struct macb *bp)
+{
+ return RX_RING_SIZE / bp->rx_buffers_per_page;
}
void macb_set_hwaddr(struct macb *bp)
@@ -587,7 +592,7 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag,
skb_put(skb, len);
for (frag = first_frag; ; frag++) {
- unsigned int frag_len = RX_BUFFER_SIZE;
+ unsigned int frag_len = bp->rx_buffer_size;
if (skb_offset + frag_len > len) {
BUG_ON(frag != last_frag);
@@ -931,11 +936,36 @@ static u32 macb_dbw(struct macb *bp)
}
}
+static void macb_init_rx_buffer_size(struct macb *bp)
+{
+ if (!macb_is_gem(bp)) {
+ bp->rx_buffer_size = MACB_RX_BUFFER_SIZE;
+ } else {
+ bp->rx_buffer_size = GEM_RX_BUFFER_SIZE;
+
+ if (bp->rx_buffer_size > PAGE_SIZE) {
+ netdev_warn(bp->dev,
+ "RX buffer cannot be bigger than PAGE_SIZE, shrinking\n");
+ bp->rx_buffer_size = PAGE_SIZE;
+ }
+ if (bp->rx_buffer_size % RX_BUFFER_MULTIPLE) {
+ netdev_warn(bp->dev,
+ "RX buffer must be multiple of %d bytes, shrinking\n",
+ RX_BUFFER_MULTIPLE);
+ bp->rx_buffer_size =
+ rounddown(bp->rx_buffer_size, RX_BUFFER_MULTIPLE);
+ }
+ bp->rx_buffer_size = max(RX_BUFFER_MULTIPLE, GEM_RX_BUFFER_SIZE);
+ }
+
+ bp->rx_buffers_per_page = PAGE_SIZE / bp->rx_buffer_size;
+}
+
static void macb_free_rings(struct macb *bp)
{
int i;
- for (i = 0; i < RX_RING_PAGES; i++) {
+ for (i = 0; i < rx_ring_pages(bp); i++) {
struct macb_rx_page *rx_page = &bp->rx_page[i];
if (!rx_page->page)
@@ -989,7 +1019,10 @@ static int macb_init_rings(struct macb *bp)
"Allocated TX ring of %d bytes at 0x%08lx (mapped %p)\n",
TX_RING_BYTES, (unsigned long)bp->tx_ring_dma, bp->tx_ring);
- bp->rx_page = kcalloc(RX_RING_PAGES, sizeof(struct macb_rx_page),
+ /* RX buffers initialization */
+ macb_init_rx_buffer_size(bp);
+
+ bp->rx_page = kcalloc(rx_ring_pages(bp), sizeof(struct macb_rx_page),
GFP_KERNEL);
if (!bp->rx_page)
goto err_alloc_rx_page;
@@ -999,7 +1032,7 @@ static int macb_init_rings(struct macb *bp)
if (!bp->tx_skb)
goto err_alloc_tx_skb;
- for (page_idx = 0, ring_idx = 0; page_idx < RX_RING_PAGES; page_idx++) {
+ for (page_idx = 0, ring_idx = 0; page_idx < rx_ring_pages(bp); page_idx++) {
page = alloc_page(GFP_KERNEL);
if (!page)
goto err_alloc_page;
@@ -1012,16 +1045,16 @@ static int macb_init_rings(struct macb *bp)
bp->rx_page[page_idx].page = page;
bp->rx_page[page_idx].phys = phys;
- for (i = 0; i < RX_BUFFERS_PER_PAGE; i++, ring_idx++) {
+ for (i = 0; i < bp->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;
+ phys += bp->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);
+ netdev_dbg(bp->dev, "Allocated %u RX buffers of size %u (%u pages)\n",
+ RX_RING_SIZE, bp->rx_buffer_size, rx_ring_pages(bp));
for (i = 0; i < TX_RING_SIZE; i++) {
bp->tx_ring[i].addr = 0;
@@ -1134,7 +1167,7 @@ static void macb_configure_dma(struct macb *bp)
if (macb_is_gem(bp)) {
dmacfg = gem_readl(bp, DMACFG) & ~GEM_BF(RXBS, -1L);
- dmacfg |= GEM_BF(RXBS, RX_BUFFER_SIZE / 64);
+ dmacfg |= GEM_BF(RXBS, bp->rx_buffer_size / RX_BUFFER_MULTIPLE);
dmacfg |= GEM_BF(FBLDO, 16);
dmacfg |= GEM_BIT(TXPBMS) | GEM_BF(RXBMS, -1L);
gem_writel(bp, DMACFG, dmacfg);
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index b4c9515..88780e2 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -562,6 +562,8 @@ struct macb {
struct macb_dma_desc *rx_ring;
struct macb_rx_page *rx_page;
void *rx_buffers;
+ size_t rx_buffer_size;
+ unsigned int rx_buffers_per_page;
unsigned int tx_head, tx_tail;
struct macb_dma_desc *tx_ring;
--
1.8.0
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/