Enforce all device constraints on the descriptor memory region.
There are several constraints on the descriptor memory, as documented
in the specification. The current code does not enforce them and/or
incorrectly enforces them.
Those constraints are:
- The address limitations on 30/32bit engines, that also apply to
the skbs.
- The 4k alignment requirement on 30/32bit engines.
- The 8k alignment requirement on 64bit engines.
Signed-off-by: Michael Buesch <mb@xxxxxxxxx>
---
It's not entirely clear if any 64bit devices exist that _really_ need the 8k
alignment. However, I think it does not hurt much if we enforce it anyway.
The patch removes the always-set-GFP_DMA-on-64bit-devices hack. The combination of
the new enforcements should be enough to keep every device happy, including those
which needed the GFP_DMA hack. The new code will dynamically check if GFP_DMA is
required, instead of statically doing it all the time.
John, please queue for the next feature release. This patch still needs a fair
amount of testing. I think the best way to get it is to simply apply it. If this
causes any regressions, we can (temporary) revert it.
This also is a candidate for a b43legacy backport.
Index: wireless-testing/drivers/net/wireless/b43/dma.c
===================================================================
--- wireless-testing.orig/drivers/net/wireless/b43/dma.c 2009-11-18 19:09:38.000000000 +0100
+++ wireless-testing/drivers/net/wireless/b43/dma.c 2009-11-18 19:21:17.000000000 +0100
@@ -383,44 +383,160 @@ 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)
{
- gfp_t flags = GFP_KERNEL;
+ unsigned int required;
+ void *base;
+ dma_addr_t dmaaddr;
- /* 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!
+ /* 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.
*/
+
if (ring->type == B43_DMA_64BIT)
- 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");
+ required = ring->nr_slots * sizeof(struct b43_dmadesc64);
+ else
+ required = ring->nr_slots * sizeof(struct b43_dmadesc32);
+ if (B43_WARN_ON(required > 0x1000))
return -ENOMEM;
- }
- memset(ring->descbase, 0, B43_DMA_RINGMEMSIZE);
+
+ 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));
return 0;
}
static void free_ringmemory(struct b43_dmaring *ring)
{
- 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);
+ b43_unmap_and_free_ringmem(ring, ring->alloc_descbase,
+ ring->alloc_dmabase, ring->alloc_descsize);
}
/* Reset the RX DMA channel */
@@ -530,29 +646,14 @@ static bool b43_dma_mapping_error(struct
if (unlikely(ssb_dma_mapping_error(ring->dev->dev, addr)))
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;
+ 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;
}
/* 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)
@@ -614,6 +715,9 @@ static int setup_rx_descbuffer(struct b4
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;
}
@@ -1246,6 +1350,9 @@ static int dma_tx_fragment(struct b43_dm
}
/* 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;
Index: wireless-testing/drivers/net/wireless/b43/dma.h
===================================================================
--- wireless-testing.orig/drivers/net/wireless/b43/dma.h 2009-11-18 19:09:38.000000000 +0100
+++ wireless-testing/drivers/net/wireless/b43/dma.h 2009-11-18 19:29:49.000000000 +0100
@@ -157,7 +157,6 @@ 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 */
@@ -243,6 +242,12 @@ 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. */
--
Greetings, Michael.
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