[PATCH] b43legacy: Fix DMA breakage from commit commit 65a21b71f948

[Larry Finger]

Following commit 65a21b71f948 ("powerpc/dma: remove dma_nommu_dma_supported"),
this driver errors with a message that "The machine/kernel does not
support the required 30-bit DMA mask." Indeed, the hardware only allows
31-bit masks. This solution is to change the fallback mask from 30-
to 31-bits for 32-bit PPC systems.

Fixes: 65a21b71f948 ("powerpc/dma: remove dma_nommu_dma_supported")
Reported-by: Aaro Koskinen <aaro.koskinen@xxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Aaro Koskinen <aaro.koskinen@xxxxxx>
Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
---
 drivers/net/wireless/broadcom/b43legacy/dma.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/broadcom/b43legacy/dma.c b/drivers/net/wireless/broadcom/b43legacy/dma.c
index 1cc25f44dd9a..75613f516e50 100644
--- a/drivers/net/wireless/broadcom/b43legacy/dma.c
+++ b/drivers/net/wireless/broadcom/b43legacy/dma.c
@@ -27,6 +27,15 @@
 #include <linux/slab.h>
 #include <net/dst.h>
 
+/* Special handling for PPC32 - The maximum DMA mask is 31 bits, and
+ * the fallback to 30 bits fails. Set the fallback at 31.
+ */
+#ifdef CONFIG_PPC32
+#define FB_DMA	31
+#else
+#define FB_DMA	30
+#endif
+
 /* 32bit DMA ops. */
 static
 struct b43legacy_dmadesc32 *op32_idx2desc(struct b43legacy_dmaring *ring,
@@ -418,7 +427,7 @@ static bool b43legacy_dma_mapping_error(struct b43legacy_dmaring *ring,
 
 	switch (ring->type) {
 	case B43legacy_DMA_30BIT:
-		if ((u64)addr + buffersize > (1ULL << 30))
+		if ((u64)addr + buffersize > (1ULL << FB_DMA))
 			goto address_error;
 		break;
 	case B43legacy_DMA_32BIT:
@@ -617,12 +626,12 @@ static u64 supported_dma_mask(struct b43legacy_wldev *dev)
 	if (tmp & B43legacy_DMA32_TXADDREXT_MASK)
 		return DMA_BIT_MASK(32);
 
-	return DMA_BIT_MASK(30);
+	return DMA_BIT_MASK(FB_DMA);
 }
 
 static enum b43legacy_dmatype dma_mask_to_engine_type(u64 dmamask)
 {
-	if (dmamask == DMA_BIT_MASK(30))
+	if (dmamask == DMA_BIT_MASK(FB_DMA))
 		return B43legacy_DMA_30BIT;
 	if (dmamask == DMA_BIT_MASK(32))
 		return B43legacy_DMA_32BIT;
@@ -802,7 +811,7 @@ static int b43legacy_dma_set_mask(struct b43legacy_wldev *dev, u64 mask)
 			continue;
 		}
 		if (mask == DMA_BIT_MASK(32)) {
-			mask = DMA_BIT_MASK(30);
+			mask = DMA_BIT_MASK(FB_DMA);
 			fallback = true;
 			continue;
 		}
-- 
2.21.0


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