Revert "b43: Enforce DMA descriptor memory constraints"

This reverts commit 9bd568a50c446433038dec2a5186c5c57c3dbd23.

That commit is shown to cause allocation failures during initialization
on some machines.

http://bugzilla.kernel.org/show_bug.cgi?id=14844

Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 46 insertions, 158 deletions

diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
index 027be275e035..88d1fd02d40a 100644
--- a/drivers/net/wireless/b43/dma.c
+++ b/drivers/net/wireless/b43/dma.c
@@ -383,160 +383,44 @@ static inline
         }
 }
 
-/* Check if a DMA region fits the device constraints.
- * Returns true, if the region is OK for usage with this device. */
-static inline bool b43_dma_address_ok(struct b43_dmaring *ring,
-                                      dma_addr_t addr, size_t size)
-{
-        switch (ring->type) {
-        case B43_DMA_30BIT:
-                if ((u64)addr + size > (1ULL << 30))
-                        return 0;
-                break;
-        case B43_DMA_32BIT:
-                if ((u64)addr + size > (1ULL << 32))
-                        return 0;
-                break;
-        case B43_DMA_64BIT:
-                /* Currently we can't have addresses beyond
-                 * 64bit in the kernel. */
-                break;
-        }
-        return 1;
-}
-
-#define is_4k_aligned(addr)     (((u64)(addr) & 0x0FFFull) == 0)
-#define is_8k_aligned(addr)     (((u64)(addr) & 0x1FFFull) == 0)
-
-static void b43_unmap_and_free_ringmem(struct b43_dmaring *ring, void *base,
-                                       dma_addr_t dmaaddr, size_t size)
-{
-        ssb_dma_unmap_single(ring->dev->dev, dmaaddr, size, DMA_TO_DEVICE);
-        free_pages((unsigned long)base, get_order(size));
-}
-
-static void * __b43_get_and_map_ringmem(struct b43_dmaring *ring,
-                                        dma_addr_t *dmaaddr, size_t size,
-                                        gfp_t gfp_flags)
-{
-        void *base;
-
-        base = (void *)__get_free_pages(gfp_flags, get_order(size));
-        if (!base)
-                return NULL;
-        memset(base, 0, size);
-        *dmaaddr = ssb_dma_map_single(ring->dev->dev, base, size,
-                                      DMA_TO_DEVICE);
-        if (ssb_dma_mapping_error(ring->dev->dev, *dmaaddr)) {
-                free_pages((unsigned long)base, get_order(size));
-                return NULL;
-        }
-
-        return base;
-}
-
-static void * b43_get_and_map_ringmem(struct b43_dmaring *ring,
-                                      dma_addr_t *dmaaddr, size_t size)
-{
-        void *base;
-
-        base = __b43_get_and_map_ringmem(ring, dmaaddr, size,
-                                         GFP_KERNEL);
-        if (!base) {
-                b43err(ring->dev->wl, "Failed to allocate or map pages "
-                       "for DMA ringmemory\n");
-                return NULL;
-        }
-        if (!b43_dma_address_ok(ring, *dmaaddr, size)) {
-                /* The memory does not fit our device constraints.
-                 * Retry with GFP_DMA set to get lower memory. */
-                b43_unmap_and_free_ringmem(ring, base, *dmaaddr, size);
-                base = __b43_get_and_map_ringmem(ring, dmaaddr, size,
-                                                 GFP_KERNEL | GFP_DMA);
-                if (!base) {
-                        b43err(ring->dev->wl, "Failed to allocate or map pages "
-                               "in the GFP_DMA region for DMA ringmemory\n");
-                        return NULL;
-                }
-                if (!b43_dma_address_ok(ring, *dmaaddr, size)) {
-                        b43_unmap_and_free_ringmem(ring, base, *dmaaddr, size);
-                        b43err(ring->dev->wl, "Failed to allocate DMA "
-                               "ringmemory that fits device constraints\n");
-                        return NULL;
-                }
-        }
-        /* We expect the memory to be 4k aligned, at least. */
-        if (B43_WARN_ON(!is_4k_aligned(*dmaaddr))) {
-                b43_unmap_and_free_ringmem(ring, base, *dmaaddr, size);
-                return NULL;
-        }
-
-        return base;
-}
-
 static int alloc_ringmemory(struct b43_dmaring *ring)
 {
-        unsigned int required;
-        void *base;
-        dma_addr_t dmaaddr;
-
-        /* There are several requirements to the descriptor ring memory:
-         * - The memory region needs to fit the address constraints for the
-         *   device (same as for frame buffers).
-         * - For 30/32bit DMA devices, the descriptor ring must be 4k aligned.
-         * - For 64bit DMA devices, the descriptor ring must be 8k aligned.
+        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
+         * 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)
-                required = ring->nr_slots * sizeof(struct b43_dmadesc64);
-        else
-                required = ring->nr_slots * sizeof(struct b43_dmadesc32);
-        if (B43_WARN_ON(required > 0x1000))
+                flags |= GFP_DMA;
+        ring->descbase = ssb_dma_alloc_consistent(ring->dev->dev,
+                                                  B43_DMA_RINGMEMSIZE,
+                                                  &(ring->dmabase), flags);
+        if (!ring->descbase) {
+                b43err(ring->dev->wl, "DMA ringmemory allocation failed\n");
                 return -ENOMEM;
-
-        ring->alloc_descsize = 0x1000;
-        base = b43_get_and_map_ringmem(ring, &dmaaddr, ring->alloc_descsize);
-        if (!base)
-                return -ENOMEM;
-        ring->alloc_descbase = base;
-        ring->alloc_dmabase = dmaaddr;
-
-        if ((ring->type != B43_DMA_64BIT) || is_8k_aligned(dmaaddr)) {
-                /* We're on <=32bit DMA, or we already got 8k aligned memory.
-                 * That's all we need, so we're fine. */
-                ring->descbase = base;
-                ring->dmabase = dmaaddr;
-                return 0;
-        }
-        b43_unmap_and_free_ringmem(ring, base, dmaaddr, ring->alloc_descsize);
-
-        /* Ok, we failed at the 8k alignment requirement.
-         * Try to force-align the memory region now. */
-        ring->alloc_descsize = 0x2000;
-        base = b43_get_and_map_ringmem(ring, &dmaaddr, ring->alloc_descsize);
-        if (!base)
-                return -ENOMEM;
-        ring->alloc_descbase = base;
-        ring->alloc_dmabase = dmaaddr;
-
-        if (is_8k_aligned(dmaaddr)) {
-                /* We're already 8k aligned. That Ok, too. */
-                ring->descbase = base;
-                ring->dmabase = dmaaddr;
-                return 0;
         }
-        /* Force-align it to 8k */
-        ring->descbase = (void *)((u8 *)base + 0x1000);
-        ring->dmabase = dmaaddr + 0x1000;
-        B43_WARN_ON(!is_8k_aligned(ring->dmabase));
+        memset(ring->descbase, 0, B43_DMA_RINGMEMSIZE);
 
         return 0;
 }
 
 static void free_ringmemory(struct b43_dmaring *ring)
 {
-        b43_unmap_and_free_ringmem(ring, ring->alloc_descbase,
-                                   ring->alloc_dmabase, ring->alloc_descsize);
+        gfp_t flags = GFP_KERNEL;
+
+        if (ring->type == B43_DMA_64BIT)
+                flags |= GFP_DMA;
+
+        ssb_dma_free_consistent(ring->dev->dev, B43_DMA_RINGMEMSIZE,
+                                ring->descbase, ring->dmabase, flags);
 }
 
 /* Reset the RX DMA channel */
@@ -646,14 +530,29 @@ static bool b43_dma_mapping_error(struct b43_dmaring *ring,
         if (unlikely(ssb_dma_mapping_error(ring->dev->dev, addr)))
                 return 1;
 
-        if (!b43_dma_address_ok(ring, addr, buffersize)) {
-                /* We can't support this address. Unmap it again. */
-                unmap_descbuffer(ring, addr, buffersize, dma_to_device);
-                return 1;
+        switch (ring->type) {
+        case B43_DMA_30BIT:
+                if ((u64)addr + buffersize > (1ULL << 30))
+                        goto address_error;
+                break;
+        case B43_DMA_32BIT:
+                if ((u64)addr + buffersize > (1ULL << 32))
+                        goto address_error;
+                break;
+        case B43_DMA_64BIT:
+                /* Currently we can't have addresses beyond
+                 * 64bit in the kernel. */
+                break;
         }
 
         /* The address is OK. */
         return 0;
+
+address_error:
+        /* We can't support this address. Unmap it again. */
+        unmap_descbuffer(ring, addr, buffersize, dma_to_device);
+
+        return 1;
 }
 
 static bool b43_rx_buffer_is_poisoned(struct b43_dmaring *ring, struct sk_buff *skb)
@@ -715,9 +614,6 @@ static int setup_rx_descbuffer(struct b43_dmaring *ring,
         meta->dmaaddr = dmaaddr;
         ring->ops->fill_descriptor(ring, desc, dmaaddr,
                                    ring->rx_buffersize, 0, 0, 0);
-        ssb_dma_sync_single_for_device(ring->dev->dev,
-                                       ring->alloc_dmabase,
-                                       ring->alloc_descsize, DMA_TO_DEVICE);
 
         return 0;
 }
@@ -1354,9 +1250,6 @@ static int dma_tx_fragment(struct b43_dmaring *ring,
         }
         /* Now transfer the whole frame. */
         wmb();
-        ssb_dma_sync_single_for_device(ring->dev->dev,
-                                       ring->alloc_dmabase,
-                                       ring->alloc_descsize, DMA_TO_DEVICE);
         ops->poke_tx(ring, next_slot(ring, slot));
         return 0;
 
diff --git a/drivers/net/wireless/b43/dma.h b/drivers/net/wireless/b43/dma.h
index e607b392314c..f7ab37c4cdbc 100644
--- a/drivers/net/wireless/b43/dma.h
+++ b/drivers/net/wireless/b43/dma.h
@@ -157,6 +157,7 @@ struct b43_dmadesc_generic {
 } __attribute__ ((__packed__));
 
 /* Misc DMA constants */
+#define B43_DMA_RINGMEMSIZE             PAGE_SIZE
 #define B43_DMA0_RX_FRAMEOFFSET         30
 
 /* DMA engine tuning knobs */
@@ -246,12 +247,6 @@ struct b43_dmaring {
         /* The QOS priority assigned to this ring. Only used for TX rings.
          * This is the mac80211 "queue" value. */
         u8 queue_prio;
-        /* Pointers and size of the originally allocated and mapped memory
-         * region for the descriptor ring. */
-        void *alloc_descbase;
-        dma_addr_t alloc_dmabase;
-        unsigned int alloc_descsize;
-        /* Pointer to our wireless device. */
         struct b43_wldev *dev;
 #ifdef CONFIG_B43_DEBUG
         /* Maximum number of used slots. */