From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= Date: Fri, 26 Aug 2011 20:41:39 +0200 Subject: [wireless-next][PATCH 2/3] b43: use 8K buffers for 64-bit DMA to workaround hardware bug In-Reply-To: <1314384100-3492-2-git-send-email-zajec5@gmail.com> References: <1314384100-3492-2-git-send-email-zajec5@gmail.com> Message-ID: <1314384100-3492-3-git-send-email-zajec5@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-wireless@vger.kernel.org, "John W. Linville" Cc: b43-dev@lists.infradead.org, David Woodhouse , Maxime Vincent , Darren , =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= Signed-off-by: Rafa? Mi?ecki --- drivers/net/wireless/b43/dma.c | 24 ++++++++++++++++-------- drivers/net/wireless/b43/dma.h | 3 ++- 2 files changed, 18 insertions(+), 9 deletions(-) diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c index e36e8b5..5e45604 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 7e20b04..315b96e 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 -- 1.7.1