From 996bc370fa5f28f0a07d6c8dee26591db2f3dea9 Mon Sep 17 00:00:00 2001 From: Larry Finger Date: Fri, 26 Aug 2011 20:41:38 +0200 Subject: b43: Relax requirement for descriptors to be in the DMA zone When 64-bit DMA was first used, there were problems with the BCM4311 (14e4:4311). The problem was "fixed" by using the GFP_DMA flag in the allocation of coherent ring descriptor memory. The original problem is now believed to have been due to bugs in the 64-bit DMA implementation in the rest of the kernel, and that those bugs have been fixed. Accordingly, the requirement for the descriptors to be in the DMA zone is relaxed. Bounce buffers are left in the DMA zone. Signed-off-by: Larry Finger Signed-off-by: Michael Buesch Signed-off-by: John W. Linville --- drivers/net/wireless/b43/dma.c | 7 ------- 1 file changed, 7 deletions(-) (limited to 'drivers/net/wireless/b43/dma.c') diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c index e76b40ddbc48..c83c4b64c60e 100644 --- a/drivers/net/wireless/b43/dma.c +++ b/drivers/net/wireless/b43/dma.c @@ -423,14 +423,7 @@ static int alloc_ringmemory(struct b43_dmaring *ring) * has shown that 4K is sufficient for the latter as long as the buffer * does not cross an 8K boundary. * - * For unknown reasons - possibly a hardware error - the BCM4311 rev - * 02, which uses 64-bit DMA, needs the ring buffer in very low memory, - * which accounts for the GFP_DMA flag below. - * - * The flags here must match the flags in free_ringmemory below! */ - if (ring->type == B43_DMA_64BIT) - flags |= GFP_DMA; ring->descbase = dma_alloc_coherent(ring->dev->dev->dma_dev, B43_DMA_RINGMEMSIZE, &(ring->dmabase), flags); -- cgit v1.2.3 From 14a8083e67653a963bb53f905044c23593026737 Mon Sep 17 00:00:00 2001 From: Rafał Miłecki Date: Fri, 26 Aug 2011 20:41:39 +0200 Subject: b43: use 8K buffers for 64-bit DMA to workaround hardware bug MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Rafał Miłecki Signed-off-by: John W. Linville --- drivers/net/wireless/b43/dma.c | 24 ++++++++++++++++-------- drivers/net/wireless/b43/dma.h | 3 ++- 2 files changed, 18 insertions(+), 9 deletions(-) (limited to 'drivers/net/wireless/b43/dma.c') diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c index c83c4b64c60e..975d96040548 100644 --- a/drivers/net/wireless/b43/dma.c +++ b/drivers/net/wireless/b43/dma.c @@ -419,26 +419,34 @@ static int alloc_ringmemory(struct b43_dmaring *ring) 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); } diff --git a/drivers/net/wireless/b43/dma.h b/drivers/net/wireless/b43/dma.h index 7e20b04fa51a..315b96ed1d90 100644 --- a/drivers/net/wireless/b43/dma.h +++ b/drivers/net/wireless/b43/dma.h @@ -161,7 +161,8 @@ struct b43_dmadesc_generic { } __packed; /* Misc DMA constants */ -#define B43_DMA_RINGMEMSIZE PAGE_SIZE +#define B43_DMA32_RINGMEMSIZE 4096 +#define B43_DMA64_RINGMEMSIZE 8192 /* Offset of frame with actual data */ #define B43_DMA0_RX_FW598_FO 38 #define B43_DMA0_RX_FW351_FO 30 -- cgit v1.2.3