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authorStefan Richter <stefanr@s5r6.in-berlin.de>2010-07-27 13:20:33 +0200
committerStefan Richter <stefanr@s5r6.in-berlin.de>2010-07-29 23:06:25 +0200
commit071595ebdc66d70219e2d1ce746016f64b2b19e7 (patch)
tree3083b0de17a6d0633420ffda1dfa04a0b4b880b2 /drivers/firewire
parent8e2b2b46ea4ca5ef790dddf78b360ed736a62d7c (diff)
downloadop-kernel-dev-071595ebdc66d70219e2d1ce746016f64b2b19e7.zip
op-kernel-dev-071595ebdc66d70219e2d1ce746016f64b2b19e7.tar.gz
firewire: ohci: use memory barriers to order descriptor updates
When we append to a DMA program, we need to ensure that the order in which initialization of the new descriptors and update of the branch_address of the old tail descriptor, as seen by the PCI device, happen as intended. Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/firewire')
-rw-r--r--drivers/firewire/ohci.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 5f6bb2c..3f59d1d 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -595,6 +595,7 @@ static int ar_context_add_page(struct ar_context *ctx)
ab->descriptor.res_count = cpu_to_le16(PAGE_SIZE - offset);
ab->descriptor.branch_address = 0;
+ wmb(); /* finish init of new descriptors before branch_address update */
ctx->last_buffer->descriptor.branch_address = cpu_to_le32(ab_bus | 1);
ctx->last_buffer->next = ab;
ctx->last_buffer = ab;
@@ -982,6 +983,8 @@ static void context_append(struct context *ctx,
d_bus = desc->buffer_bus + (d - desc->buffer) * sizeof(*d);
desc->used += (z + extra) * sizeof(*d);
+
+ wmb(); /* finish init of new descriptors before branch_address update */
ctx->prev->branch_address = cpu_to_le32(d_bus | z);
ctx->prev = find_branch_descriptor(d, z);
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