Date: Sun, 4 Feb 2007 20:54:57 +0100 (CET) From: Stefan Richter Subject: 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 --- drivers/ieee1394/sbp2.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) Index: foo/drivers/ieee1394/sbp2.c =================================================================== --- foo.orig/drivers/ieee1394/sbp2.c +++ foo/drivers/ieee1394/sbp2.c @@ -489,7 +489,7 @@ static int sbp2util_create_command_orb_p 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 @@ static void sbp2util_remove_command_orb_ 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 @@ static void sbp2_link_orb_command(struct 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 @@ static int sbp2_handle_status_write(stru 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 @@ static void sbp2scsi_complete_all_comman 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 @@ static int sbp2scsi_abort(struct scsi_cm 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;