On Wed, 24 Aug 2011 17:02:52 -0500 Larry Finger <Larry.Finger@xxxxxxxxxxxx> wrote: > 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 <Larry.Finger@xxxxxxxxxxxx> > --- > > John, > > This material is for next. John, please apply this even though it's marked RFC, unless somebody objects in reasonable time, which I don't expect. You can also add Signed-off-by: Michael Buesch <m@xxxxxxx> if you desire. > Index: wireless-testing-new/drivers/net/wireless/b43/dma.c > =================================================================== > --- wireless-testing-new.orig/drivers/net/wireless/b43/dma.c > +++ wireless-testing-new/drivers/net/wireless/b43/dma.c > @@ -393,14 +393,7 @@ static int alloc_ringmemory(struct b43_d > * 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); > -- Greetings, Michael. -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
