ieee1394: sbp2: optimize DMA direction of s/g tables
Unlike the name suggests, "cmd->scatter_gather_element" holds only the
s/g table, not the actual s/g elements. Since the table is only read
but never written by the device, DMA_BIDIRECTIONAL can be replaced by
DMA_TO_DEVICE which may be cheaper on some architectures.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/ieee1394/sbp2.c b/drivers/ieee1394/sbp2.c
index e15b5d7..cae3816 100644
--- a/drivers/ieee1394/sbp2.c
+++ b/drivers/ieee1394/sbp2.c
@@ -489,7 +489,7 @@
cmd->sge_dma = dma_map_single(hi->host->device.parent,
&cmd->scatter_gather_element,
sizeof(cmd->scatter_gather_element),
- DMA_BIDIRECTIONAL);
+ DMA_TO_DEVICE);
INIT_LIST_HEAD(&cmd->list);
list_add_tail(&cmd->list, &lu->cmd_orb_completed);
}
@@ -514,7 +514,7 @@
DMA_TO_DEVICE);
dma_unmap_single(host->device.parent, cmd->sge_dma,
sizeof(cmd->scatter_gather_element),
- DMA_BIDIRECTIONAL);
+ DMA_TO_DEVICE);
kfree(cmd);
}
spin_unlock_irqrestore(&lu->cmd_orb_lock, flags);
@@ -1633,7 +1633,7 @@
DMA_TO_DEVICE);
dma_sync_single_for_device(hi->host->device.parent, cmd->sge_dma,
sizeof(cmd->scatter_gather_element),
- DMA_BIDIRECTIONAL);
+ DMA_TO_DEVICE);
/* check to see if there are any previous orbs to use */
spin_lock_irqsave(&lu->cmd_orb_lock, flags);
@@ -1799,7 +1799,7 @@
DMA_TO_DEVICE);
dma_sync_single_for_cpu(hi->host->device.parent, cmd->sge_dma,
sizeof(cmd->scatter_gather_element),
- DMA_BIDIRECTIONAL);
+ DMA_TO_DEVICE);
/* Grab SCSI command pointers and check status. */
/*
* FIXME: If the src field in the status is 1, the ORB DMA must
@@ -1931,7 +1931,7 @@
DMA_TO_DEVICE);
dma_sync_single_for_cpu(hi->host->device.parent, cmd->sge_dma,
sizeof(cmd->scatter_gather_element),
- DMA_BIDIRECTIONAL);
+ DMA_TO_DEVICE);
sbp2util_mark_command_completed(lu, cmd);
if (cmd->Current_SCpnt) {
cmd->Current_SCpnt->result = status << 16;
@@ -2062,7 +2062,7 @@
dma_sync_single_for_cpu(hi->host->device.parent,
cmd->sge_dma,
sizeof(cmd->scatter_gather_element),
- DMA_BIDIRECTIONAL);
+ DMA_TO_DEVICE);
sbp2util_mark_command_completed(lu, cmd);
if (cmd->Current_SCpnt) {
cmd->Current_SCpnt->result = DID_ABORT << 16;
