Attachment 154609 Details for Bug 235542 – [PATCH 2.6.20] ieee1394: sbp2: optimize DMA direction of s/g tables

[patch] [PATCH 2.6.20] ieee1394: sbp2: optimize DMA direction of s/g tables

276-ieee1394-sbp2-optimize-dma-direction-for-sg-tables.patch (text/plain), 2.78 KB, created by Stefan Richter on 2007-05-13 13:34:57 UTC

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Creator: Stefan Richter

Created: 2007-05-13 13:34:57 UTC

Size: 2.78 KB

patch

obsolete

>Date: Sun, 4 Feb 2007 20:54:57 +0100 (CET)
>From: Stefan Richter <stefanr@s5r6.in-berlin.de>
>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 <stefanr@s5r6.in-berlin.de>
>Index: linux-2.6.20/drivers/ieee1394/sbp2.c
>===================================================================
>--- linux-2.6.20.orig/drivers/ieee1394/sbp2.c	2007-05-13 15:29:51.000000000 +0200
>+++ linux-2.6.20/drivers/ieee1394/sbp2.c	2007-05-13 15:30:33.000000000 +0200
>@@ -497,7 +497,7 @@ 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);
> 	}
>@@ -522,7 +522,7 @@ 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);
>@@ -1634,7 +1634,7 @@ 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);
>@@ -1800,7 +1800,7 @@ 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
>@@ -1932,7 +1932,7 @@ 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;
>@@ -2064,7 +2064,7 @@ 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;

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