Commit 5b876618 authored by Roland Vossen's avatar Roland Vossen Committed by Greg Kroah-Hartman

staging: brcm80211: added clarification on softmac dma alignment

Descriptor ring can only start at 8KB alignment, this requirement
is dictated by DMA hardware.
Reported-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarRoland Vossen <rvossen@broadcom.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 7d9e0b9a
......@@ -24,8 +24,8 @@
#include "dma.h"
/*
* Each descriptor ring must be 8kB aligned, and fit within a
* contiguous 8kB physical address.
* DMA hardware requires each descriptor ring to be 8kB aligned, and fit within
* a contiguous 8kB physical address.
*/
#define D64RINGALIGN_BITS 13
#define D64MAXRINGSZ (1 << D64RINGALIGN_BITS)
......@@ -440,6 +440,10 @@ static bool _dma_descriptor_align(struct dma_info *di)
return true;
}
/*
* Descriptor table must start at the DMA hardware dictated alignment, so
* allocated memory must be large enough to support this requirement.
*/
static void *dma_alloc_consistent(struct pci_dev *pdev, uint size,
u16 align_bits, uint *alloced,
dma_addr_t *pap)
......
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