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Subject[PATCH] firewire: fw-ohci: optimize initialization of ar context
Sync only the parts for CPU which are actually accessed by the CPU.
Replace a memset by direct assignment.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
drivers/firewire/fw-ohci.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)

Index: linux/drivers/firewire/fw-ohci.c
===================================================================
--- linux.orig/drivers/firewire/fw-ohci.c
+++ linux/drivers/firewire/fw-ohci.c
@@ -258,19 +258,21 @@ static int ar_context_add_page(struct ar
free_page((unsigned long) ab);
return -ENOMEM;
}
- dma_sync_single_for_cpu(dev, ab_bus, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ dma_sync_single_for_cpu(dev, ab_bus, sizeof(ab->descriptor),
+ DMA_BIDIRECTIONAL);

- memset(&ab->descriptor, 0, sizeof(ab->descriptor));
- ab->descriptor.control = cpu_to_le16(DESCRIPTOR_INPUT_MORE |
- DESCRIPTOR_STATUS |
- DESCRIPTOR_BRANCH_ALWAYS);
offset = offsetof(struct ar_buffer, data);
- ab->descriptor.req_count = cpu_to_le16(PAGE_SIZE - offset);
- ab->descriptor.data_address = cpu_to_le32(ab_bus + offset);
- ab->descriptor.res_count = cpu_to_le16(PAGE_SIZE - offset);
- ab->descriptor.branch_address = 0;
+ ab->descriptor.req_count = cpu_to_le16(PAGE_SIZE - offset);
+ ab->descriptor.control = cpu_to_le16(DESCRIPTOR_INPUT_MORE |
+ DESCRIPTOR_STATUS |
+ DESCRIPTOR_BRANCH_ALWAYS);
+ ab->descriptor.data_address = cpu_to_le32(ab_bus + offset);
+ ab->descriptor.branch_address = 0;
+ ab->descriptor.res_count = cpu_to_le16(PAGE_SIZE - offset);
+ ab->descriptor.transfer_status = 0;

- dma_sync_single_for_device(dev, ab_bus, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ dma_sync_single_for_device(dev, ab_bus, sizeof(ab->descriptor),
+ DMA_BIDIRECTIONAL);

ctx->last_buffer->descriptor.branch_address = cpu_to_le32(ab_bus | 1);
ctx->last_buffer->next = ab;
--
Stefan Richter
-=====-=-=== =-=- =----
http://arcgraph.de/sr/
-
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