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[PATCH] b44: alternate allocation option for DMA descriptors
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This is a (final?) hack to support the odd DMA allocation requirements
of the b44 hardware.  The b44 hardware has a 30-bit DMA mask.  On x86,
anything less than a 32-bit DMA mask forces allocations into the 16MB
GFP_DMA range.  The memory there is somewhat limited, often resulting
in an inability to initialize the b44 driver.

This hack uses streaming DMA allocation APIs in order to provide an
alternative in case the GFP_DMA allocation fails.  It is somewhat ugly,
but not much worse than the similar existing hacks to support SKB
allocations in the same driver.  FWIW, I have received positive
feedback on this from several Fedora users.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
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John W. Linville authored and Jeff Garzik committed Oct 19, 2005
1 parent df49898 commit 9f38c63
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Showing 2 changed files with 128 additions and 8 deletions.
134 changes: 126 additions & 8 deletions drivers/net/b44.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -106,6 +106,29 @@ static int b44_poll(struct net_device *dev, int *budget);
static void b44_poll_controller(struct net_device *dev);
#endif

static int dma_desc_align_mask;
static int dma_desc_sync_size;

static inline void b44_sync_dma_desc_for_device(struct pci_dev *pdev,
dma_addr_t dma_base,
unsigned long offset,
enum dma_data_direction dir)
{
dma_sync_single_range_for_device(&pdev->dev, dma_base,
offset & dma_desc_align_mask,
dma_desc_sync_size, dir);
}

static inline void b44_sync_dma_desc_for_cpu(struct pci_dev *pdev,
dma_addr_t dma_base,
unsigned long offset,
enum dma_data_direction dir)
{
dma_sync_single_range_for_cpu(&pdev->dev, dma_base,
offset & dma_desc_align_mask,
dma_desc_sync_size, dir);
}

static inline unsigned long br32(const struct b44 *bp, unsigned long reg)
{
return readl(bp->regs + reg);
Expand Down Expand Up @@ -668,6 +691,11 @@ static int b44_alloc_rx_skb(struct b44 *bp, int src_idx, u32 dest_idx_unmasked)
dp->ctrl = cpu_to_le32(ctrl);
dp->addr = cpu_to_le32((u32) mapping + bp->rx_offset + bp->dma_offset);

if (bp->flags & B44_FLAG_RX_RING_HACK)
b44_sync_dma_desc_for_device(bp->pdev, bp->rx_ring_dma,
dest_idx * sizeof(dp),
DMA_BIDIRECTIONAL);

return RX_PKT_BUF_SZ;
}

Expand All @@ -692,6 +720,11 @@ static void b44_recycle_rx(struct b44 *bp, int src_idx, u32 dest_idx_unmasked)
pci_unmap_addr_set(dest_map, mapping,
pci_unmap_addr(src_map, mapping));

if (bp->flags & B44_FLAG_RX_RING_HACK)
b44_sync_dma_desc_for_cpu(bp->pdev, bp->rx_ring_dma,
src_idx * sizeof(src_desc),
DMA_BIDIRECTIONAL);

ctrl = src_desc->ctrl;
if (dest_idx == (B44_RX_RING_SIZE - 1))
ctrl |= cpu_to_le32(DESC_CTRL_EOT);
Expand All @@ -700,8 +733,14 @@ static void b44_recycle_rx(struct b44 *bp, int src_idx, u32 dest_idx_unmasked)

dest_desc->ctrl = ctrl;
dest_desc->addr = src_desc->addr;

src_map->skb = NULL;

if (bp->flags & B44_FLAG_RX_RING_HACK)
b44_sync_dma_desc_for_device(bp->pdev, bp->rx_ring_dma,
dest_idx * sizeof(dest_desc),
DMA_BIDIRECTIONAL);

pci_dma_sync_single_for_device(bp->pdev, src_desc->addr,
RX_PKT_BUF_SZ,
PCI_DMA_FROMDEVICE);
Expand Down Expand Up @@ -959,6 +998,11 @@ static int b44_start_xmit(struct sk_buff *skb, struct net_device *dev)
bp->tx_ring[entry].ctrl = cpu_to_le32(ctrl);
bp->tx_ring[entry].addr = cpu_to_le32((u32) mapping+bp->dma_offset);

if (bp->flags & B44_FLAG_TX_RING_HACK)
b44_sync_dma_desc_for_device(bp->pdev, bp->tx_ring_dma,
entry * sizeof(bp->tx_ring[0]),
DMA_TO_DEVICE);

entry = NEXT_TX(entry);

bp->tx_prod = entry;
Expand Down Expand Up @@ -1064,6 +1108,16 @@ static void b44_init_rings(struct b44 *bp)
memset(bp->rx_ring, 0, B44_RX_RING_BYTES);
memset(bp->tx_ring, 0, B44_TX_RING_BYTES);

if (bp->flags & B44_FLAG_RX_RING_HACK)
dma_sync_single_for_device(&bp->pdev->dev, bp->rx_ring_dma,
DMA_TABLE_BYTES,
PCI_DMA_BIDIRECTIONAL);

if (bp->flags & B44_FLAG_TX_RING_HACK)
dma_sync_single_for_device(&bp->pdev->dev, bp->tx_ring_dma,
DMA_TABLE_BYTES,
PCI_DMA_TODEVICE);

for (i = 0; i < bp->rx_pending; i++) {
if (b44_alloc_rx_skb(bp, -1, i) < 0)
break;
Expand All @@ -1085,14 +1139,28 @@ static void b44_free_consistent(struct b44 *bp)
bp->tx_buffers = NULL;
}
if (bp->rx_ring) {
pci_free_consistent(bp->pdev, DMA_TABLE_BYTES,
bp->rx_ring, bp->rx_ring_dma);
if (bp->flags & B44_FLAG_RX_RING_HACK) {
dma_unmap_single(&bp->pdev->dev, bp->rx_ring_dma,
DMA_TABLE_BYTES,
DMA_BIDIRECTIONAL);
kfree(bp->rx_ring);
} else
pci_free_consistent(bp->pdev, DMA_TABLE_BYTES,
bp->rx_ring, bp->rx_ring_dma);
bp->rx_ring = NULL;
bp->flags &= ~B44_FLAG_RX_RING_HACK;
}
if (bp->tx_ring) {
pci_free_consistent(bp->pdev, DMA_TABLE_BYTES,
bp->tx_ring, bp->tx_ring_dma);
if (bp->flags & B44_FLAG_TX_RING_HACK) {
dma_unmap_single(&bp->pdev->dev, bp->tx_ring_dma,
DMA_TABLE_BYTES,
DMA_TO_DEVICE);
kfree(bp->tx_ring);
} else
pci_free_consistent(bp->pdev, DMA_TABLE_BYTES,
bp->tx_ring, bp->tx_ring_dma);
bp->tx_ring = NULL;
bp->flags &= ~B44_FLAG_TX_RING_HACK;
}
}

Expand All @@ -1118,12 +1186,56 @@ static int b44_alloc_consistent(struct b44 *bp)

size = DMA_TABLE_BYTES;
bp->rx_ring = pci_alloc_consistent(bp->pdev, size, &bp->rx_ring_dma);
if (!bp->rx_ring)
goto out_err;
if (!bp->rx_ring) {
/* Allocation may have failed due to pci_alloc_consistent
insisting on use of GFP_DMA, which is more restrictive
than necessary... */
struct dma_desc *rx_ring;
dma_addr_t rx_ring_dma;

if (!(rx_ring = (struct dma_desc *)kmalloc(size, GFP_KERNEL)))
goto out_err;

memset(rx_ring, 0, size);
rx_ring_dma = dma_map_single(&bp->pdev->dev, rx_ring,
DMA_TABLE_BYTES,
DMA_BIDIRECTIONAL);

if (rx_ring_dma + size > B44_DMA_MASK) {
kfree(rx_ring);
goto out_err;
}

bp->rx_ring = rx_ring;
bp->rx_ring_dma = rx_ring_dma;
bp->flags |= B44_FLAG_RX_RING_HACK;
}

bp->tx_ring = pci_alloc_consistent(bp->pdev, size, &bp->tx_ring_dma);
if (!bp->tx_ring)
goto out_err;
if (!bp->tx_ring) {
/* Allocation may have failed due to pci_alloc_consistent
insisting on use of GFP_DMA, which is more restrictive
than necessary... */
struct dma_desc *tx_ring;
dma_addr_t tx_ring_dma;

if (!(tx_ring = (struct dma_desc *)kmalloc(size, GFP_KERNEL)))
goto out_err;

memset(tx_ring, 0, size);
tx_ring_dma = dma_map_single(&bp->pdev->dev, tx_ring,
DMA_TABLE_BYTES,
DMA_TO_DEVICE);

if (tx_ring_dma + size > B44_DMA_MASK) {
kfree(tx_ring);
goto out_err;
}

bp->tx_ring = tx_ring;
bp->tx_ring_dma = tx_ring_dma;
bp->flags |= B44_FLAG_TX_RING_HACK;
}

return 0;

Expand Down Expand Up @@ -1973,6 +2085,12 @@ static struct pci_driver b44_driver = {

static int __init b44_init(void)
{
unsigned int dma_desc_align_size = dma_get_cache_alignment();

/* Setup paramaters for syncing RX/TX DMA descriptors */
dma_desc_align_mask = ~(dma_desc_align_size - 1);
dma_desc_sync_size = max(dma_desc_align_size, sizeof(struct dma_desc));

return pci_module_init(&b44_driver);
}

Expand Down
2 changes: 2 additions & 0 deletions drivers/net/b44.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -400,6 +400,8 @@ struct b44 {
#define B44_FLAG_ADV_100HALF 0x04000000
#define B44_FLAG_ADV_100FULL 0x08000000
#define B44_FLAG_INTERNAL_PHY 0x10000000
#define B44_FLAG_RX_RING_HACK 0x20000000
#define B44_FLAG_TX_RING_HACK 0x40000000

u32 rx_offset;

Expand Down

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