[PATCH 2/2] b43: fix DMA on some bugged hardware

[Michael Büsch]

On Wed, 10 Aug 2011 18:11:28 +0200
> diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
> index 0953ce1..9a2b678 100644
> --- a/drivers/net/wireless/b43/dma.c
> +++ b/drivers/net/wireless/b43/dma.c
> @@ -174,7 +174,10 @@ static void op64_fill_descriptor(struct b43_dmaring *ring,
>  	addrhi = (((u64) dmaaddr >> 32) & ~SSB_DMA_TRANSLATION_MASK);
>  	addrext = (((u64) dmaaddr >> 32) & SSB_DMA_TRANSLATION_MASK)
>  	    >> SSB_DMA_TRANSLATION_SHIFT;
> -	addrhi |= ring->dev->dma.translation;
> +	if (ring->dev->dma.translation_in_low)
> +		addrlo |= ring->dev->dma.translation;
> +	else
> +		addrhi |= ring->dev->dma.translation;
>  	if (slot == ring->nr_slots - 1)
>  		ctl0 |= B43_DMA64_DCTL0_DTABLEEND;
>  	if (start)
> @@ -656,10 +659,12 @@ static int alloc_initial_descbuffers(struct b43_dmaring *ring)
>  static int dmacontroller_setup(struct b43_dmaring *ring)
>  {
>  	int err = 0;
> +	int tmp;
>  	u32 value;
>  	u32 addrext;
>  	u32 trans = ring->dev->dma.translation;
>  	bool parity = ring->dev->dma.parity;
> +	u32 addrs[2];
>  
>  	if (ring->tx) {
>  		if (ring->type == B43_DMA_64BIT) {
> @@ -673,12 +678,14 @@ static int dmacontroller_setup(struct b43_dmaring *ring)
>  			if (!parity)
>  				value |= B43_DMA64_TXPARITYDISABLE;
>  			b43_dma_write(ring, B43_DMA64_TXCTL, value);
> -			b43_dma_write(ring, B43_DMA64_TXRINGLO,
> -				      (ringbase & 0xFFFFFFFF));
> -			b43_dma_write(ring, B43_DMA64_TXRINGHI,
> -				      ((ringbase >> 32) &
> -				       ~SSB_DMA_TRANSLATION_MASK)
> -				      | trans);
> +
> +			addrs[0] = ringbase & 0xFFFFFFFF;
> +			addrs[1] = ringbase >> 32;
> +			tmp = ring->dev->dma.translation_in_low ? 0 : 1;
> +			addrs[tmp] &= ~SSB_DMA_TRANSLATION_MASK;
> +			addrs[tmp] |= trans;
> +			b43_dma_write(ring, B43_DMA64_TXRINGLO, addrs[0]);
> +			b43_dma_write(ring, B43_DMA64_TXRINGHI, addrs[1]);
>  		} else {
>  			u32 ringbase = (u32) (ring->dmabase);
>  
> @@ -710,12 +717,15 @@ static int dmacontroller_setup(struct b43_dmaring *ring)
>  			if (!parity)
>  				value |= B43_DMA64_RXPARITYDISABLE;
>  			b43_dma_write(ring, B43_DMA64_RXCTL, value);
> -			b43_dma_write(ring, B43_DMA64_RXRINGLO,
> -				      (ringbase & 0xFFFFFFFF));
> -			b43_dma_write(ring, B43_DMA64_RXRINGHI,
> -				      ((ringbase >> 32) &
> -				       ~SSB_DMA_TRANSLATION_MASK)
> -				      | trans);
> +
> +			addrs[0] = ringbase & 0xFFFFFFFF;
> +			addrs[1] = ringbase >> 32;
> +			tmp = ring->dev->dma.translation_in_low ? 0 : 1;
> +			addrs[tmp] &= ~SSB_DMA_TRANSLATION_MASK;
> +			addrs[tmp] |= trans;
> +			b43_dma_write(ring, B43_DMA64_RXRINGLO, addrs[0]);
> +			b43_dma_write(ring, B43_DMA64_RXRINGHI, addrs[1]);
> +
>  			b43_dma_write(ring, B43_DMA64_RXINDEX, ring->nr_slots *
>  				      sizeof(struct b43_dmadesc64));
>  		} else {
> @@ -1052,6 +1062,21 @@ static int b43_dma_set_mask(struct b43_wldev *dev, u64 mask)
>  	return 0;
>  }


This doesn't look correct to me for several reasons:

In the fill-op the address is not masked correctly with the translation mask.
In both the fill-op and both ring setups, the actual address extension bits
are always taken from the address's high word. I guess the extension should
be the low word bits for devices where we use the low word. That's the only
thing that would make sense. But hey, it's not that we have sane hardware here.
So this has to be checked.

-- 
Greetings, Michael.