Commit 2446a79f authored by Stefan Richter's avatar Stefan Richter
Browse files

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: default avatarStefan Richter <stefanr@s5r6.in-berlin.de>
parent 0555659d

drivers/ieee1394/sbp2.c

+6 −6
Original line number Diff line number Diff line
@@ -489,7 +489,7 @@ static int sbp2util_create_command_orb_pool(struct sbp2_lu *lu) 
		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_pool(struct sbp2_lu *lu) 
					 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 sbp2_lu *lu, 
				   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(struct hpsb_host *host, int nodeid, 
					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_commands(struct sbp2_lu *lu, u32 status) 
					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_cmnd *SCpnt) 
			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;

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