[PATCH] firewire: fw-ohci: optimize initialization of ar context

[Stefan Richter <stefanr@s5r6.in-berlin.de>]

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/