b43: use 8K buffers for 64-bit DMA to workaround hardware bug
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
index c83c4b6..975d960 100644
--- a/drivers/net/wireless/b43/dma.c
+++ b/drivers/net/wireless/b43/dma.c
@@ -419,26 +419,34 @@
gfp_t flags = GFP_KERNEL;
/* The specs call for 4K buffers for 30- and 32-bit DMA with 4K
- * alignment and 8K buffers for 64-bit DMA with 8K alignment. Testing
- * has shown that 4K is sufficient for the latter as long as the buffer
- * does not cross an 8K boundary.
- *
+ * alignment and 8K buffers for 64-bit DMA with 8K alignment.
+ * In practice we could use smaller buffers for the latter, but the
+ * alignment is really important because of the hardware bug. If bit
+ * 0x00001000 is used in DMA address, some hardware (like BCM4331)
+ * copies that bit into B43_DMA64_RXSTATUS and we get false values from
+ * B43_DMA64_RXSTATDPTR. Let's just use 8K buffers even if we don't use
+ * more than 256 slots for ring.
*/
+ u16 ring_mem_size = (ring->type == B43_DMA_64BIT) ?
+ B43_DMA64_RINGMEMSIZE : B43_DMA32_RINGMEMSIZE;
+
ring->descbase = dma_alloc_coherent(ring->dev->dev->dma_dev,
- B43_DMA_RINGMEMSIZE,
- &(ring->dmabase), flags);
+ ring_mem_size, &(ring->dmabase),
+ flags);
if (!ring->descbase) {
b43err(ring->dev->wl, "DMA ringmemory allocation failed\n");
return -ENOMEM;
}
- memset(ring->descbase, 0, B43_DMA_RINGMEMSIZE);
+ memset(ring->descbase, 0, ring_mem_size);
return 0;
}
static void free_ringmemory(struct b43_dmaring *ring)
{
- dma_free_coherent(ring->dev->dev->dma_dev, B43_DMA_RINGMEMSIZE,
+ u16 ring_mem_size = (ring->type == B43_DMA_64BIT) ?
+ B43_DMA64_RINGMEMSIZE : B43_DMA32_RINGMEMSIZE;
+ dma_free_coherent(ring->dev->dev->dma_dev, ring_mem_size,
ring->descbase, ring->dmabase);
}