Commit 1033b3ea authored by Michael Buesch's avatar Michael Buesch Committed by John W. Linville
Browse files

b43: Workaround DMA quirks

Some mainboards/CPUs don't allow DMA masks bigger than a certain limit.
Some VIA crap^h^h^h^hdevices have an upper limit of 0xFFFFFFFF. So in this
case a 64-bit b43 device would always fail to acquire the mask.
Implement a workaround to fallback to lower DMA mask, as we can always
also support a lower mask.

Signed-off-by: default avatarMichael Buesch <>
Signed-off-by: default avatarJohn W. Linville <>
parent 0da926f0
......@@ -980,6 +980,42 @@ void b43_dma_free(struct b43_wldev *dev)
destroy_ring(dma, tx_ring_mcast);
static int b43_dma_set_mask(struct b43_wldev *dev, u64 mask)
u64 orig_mask = mask;
bool fallback = 0;
int err;
/* Try to set the DMA mask. If it fails, try falling back to a
* lower mask, as we can always also support a lower one. */
while (1) {
err = ssb_dma_set_mask(dev->dev, mask);
if (!err)
if (mask == DMA_64BIT_MASK) {
mask = DMA_32BIT_MASK;
fallback = 1;
if (mask == DMA_32BIT_MASK) {
mask = DMA_30BIT_MASK;
fallback = 1;
b43err(dev->wl, "The machine/kernel does not support "
"the required %u-bit DMA mask\n",
(unsigned int)dma_mask_to_engine_type(orig_mask));
if (fallback) {
b43info(dev->wl, "DMA mask fallback from %u-bit to %u-bit\n",
(unsigned int)dma_mask_to_engine_type(orig_mask),
(unsigned int)dma_mask_to_engine_type(mask));
return 0;
int b43_dma_init(struct b43_wldev *dev)
struct b43_dma *dma = &dev->dma;
......@@ -989,14 +1025,9 @@ int b43_dma_init(struct b43_wldev *dev)
dmamask = supported_dma_mask(dev);
type = dma_mask_to_engine_type(dmamask);
err = ssb_dma_set_mask(dev->dev, dmamask);
if (err) {
b43err(dev->wl, "The machine/kernel does not support "
"the required DMA mask (0x%08X%08X)\n",
(unsigned int)((dmamask & 0xFFFFFFFF00000000ULL) >> 32),
(unsigned int)(dmamask & 0x00000000FFFFFFFFULL));
err = b43_dma_set_mask(dev, dmamask);
if (err)
return err;
err = -ENOMEM;
/* setup TX DMA channels. */
Supports Markdown
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment