Return-path: Received: from mail-gx0-f174.google.com ([209.85.161.174]:37211 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751693Ab1HXPzI (ORCPT ); Wed, 24 Aug 2011 11:55:08 -0400 Received: by gxk21 with SMTP id 21so970857gxk.19 for ; Wed, 24 Aug 2011 08:55:07 -0700 (PDT) From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= To: linux-wireless@vger.kernel.org Cc: b43-dev@lists.infradead.org, David Woodhouse , =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= Subject: [RFT][PATCH] b43: use 8K buffers for 64-bit DMA to workaround hardware bug Date: Wed, 24 Aug 2011 17:57:18 +0200 Message-Id: <1314201438-12125-1-git-send-email-zajec5@gmail.com> (sfid-20110824_175511_258981_C4139D46) Sender: linux-wireless-owner@vger.kernel.org List-ID: --- David: can you give it a try? --- drivers/net/wireless/b43/dma.c | 33 ++++++++++++++++++++------------- drivers/net/wireless/b43/dma.h | 3 ++- 2 files changed, 22 insertions(+), 14 deletions(-) diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c index 5151c7f..ee583b2 100644 --- a/drivers/net/wireless/b43/dma.c +++ b/drivers/net/wireless/b43/dma.c @@ -386,36 +386,43 @@ static inline 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. - * - * For unknown reasons - possibly a hardware error - the BCM4311 rev + * 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; + + /* 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! */ + gfp_t flags = GFP_KERNEL; 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); + 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 546d19c..55244e7 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 -- 1.7.3.4