[PATCH] ieee1394: sbp2: stricter dma_sync

[Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx>]

On  5 Aug, Boaz Harrosh wrote:
> Stefan Richter wrote:
>> Boaz Harrosh wrote:
>>> From re-inspecting the code I can see that the struct sbp2_command_orb
>>> might have problems with none DMA coherent ARCHs.
>> 
>> Hmm.  This would be a bug.  But from what I see while scrolling through
>> fw-sbp2 and through sbp2, they both do it right.  Well, to be very
>> strict, sbp2 should dma_sync_single_for_cpu() at a slightly different
>> place than it does now.  I shall patch this.
>> 
> 
> Yes I agree with you. Keep me posted I'll review the code


Two dma_sync_single_for_cpu() were called in the wrong place.
Luckily they were merely for DMA_TO_DEVICE, hence nobody noticed.

Also reorder the matching dma_sync_single_for_device() a little bit
so that they reside in the same functions as their counterparts.
This also avoids syncing the s/g table for requests which don't use it.

Signed-off-by: Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx>
---
 drivers/ieee1394/sbp2.c |   33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

On a related note, sbp2 lacks error checks for the DMA mapping when the
ORB pool is created and when the request buffer is mapped.  I leave that
as a ToDo for sometime later.

Index: linux-2.6.27-rc2/drivers/ieee1394/sbp2.c
===================================================================
--- linux-2.6.27-rc2.orig/drivers/ieee1394/sbp2.c
+++ linux-2.6.27-rc2/drivers/ieee1394/sbp2.c
@@ -1522,6 +1522,10 @@ static void sbp2_prep_command_orb_sg(str
 		orb->misc |= ORB_SET_PAGE_TABLE_PRESENT(0x1);
 		orb->data_descriptor_lo = cmd->sge_dma;
 
+		dma_sync_single_for_cpu(hi->host->device.parent, cmd->sge_dma,
+					sizeof(cmd->scatter_gather_element),
+					DMA_TO_DEVICE);
+
 		/* loop through and fill out our SBP-2 page tables
 		 * (and split up anything too large) */
 		for (i = 0, sg_count = 0; i < count; i++, sg = sg_next(sg)) {
@@ -1548,6 +1552,11 @@ static void sbp2_prep_command_orb_sg(str
 		sbp2util_cpu_to_be32_buffer(sg_element,
 				(sizeof(struct sbp2_unrestricted_page_table)) *
 				sg_count);
+
+		dma_sync_single_for_device(hi->host->device.parent,
+					   cmd->sge_dma,
+					   sizeof(cmd->scatter_gather_element),
+					   DMA_TO_DEVICE);
 	}
 }
 
@@ -1555,12 +1564,14 @@ static void sbp2_create_command_orb(stru
 				    struct sbp2_command_info *cmd,
 				    struct scsi_cmnd *SCpnt)
 {
-	struct sbp2_fwhost_info *hi = lu->hi;
+	struct device *dev = lu->hi->host->device.parent;
 	struct sbp2_command_orb *orb = &cmd->command_orb;
 	u32 orb_direction;
 	unsigned int scsi_request_bufflen = scsi_bufflen(SCpnt);
 	enum dma_data_direction dma_dir = SCpnt->sc_data_direction;
 
+	dma_sync_single_for_cpu(dev, cmd->command_orb_dma,
+				sizeof(struct sbp2_command_orb), DMA_TO_DEVICE);
 	/*
 	 * Set-up our command ORB.
 	 *
@@ -1592,7 +1603,7 @@ static void sbp2_create_command_orb(stru
 		orb->data_descriptor_lo = 0x0;
 		orb->misc |= ORB_SET_DIRECTION(1);
 	} else
-		sbp2_prep_command_orb_sg(orb, hi, cmd, scsi_sg_count(SCpnt),
+		sbp2_prep_command_orb_sg(orb, lu->hi, cmd, scsi_sg_count(SCpnt),
 					 scsi_sglist(SCpnt),
 					 orb_direction, dma_dir);
 
@@ -1600,6 +1611,9 @@ static void sbp2_create_command_orb(stru
 
 	memset(orb->cdb, 0, sizeof(orb->cdb));
 	memcpy(orb->cdb, SCpnt->cmnd, SCpnt->cmd_len);
+
+	dma_sync_single_for_device(dev, cmd->command_orb_dma,
+			sizeof(struct sbp2_command_orb), DMA_TO_DEVICE);
 }
 
 static void sbp2_link_orb_command(struct sbp2_lu *lu,
@@ -1613,14 +1627,6 @@ static void sbp2_link_orb_command(struct
 	size_t length;
 	unsigned long flags;
 
-	dma_sync_single_for_device(hi->host->device.parent,
-				   cmd->command_orb_dma,
-				   sizeof(struct sbp2_command_orb),
-				   DMA_TO_DEVICE);
-	dma_sync_single_for_device(hi->host->device.parent, cmd->sge_dma,
-				   sizeof(cmd->scatter_gather_element),
-				   DMA_TO_DEVICE);
-
 	/* check to see if there are any previous orbs to use */
 	spin_lock_irqsave(&lu->cmd_orb_lock, flags);
 	last_orb = lu->last_orb;
@@ -1778,13 +1784,6 @@ static int sbp2_handle_status_write(stru
 	else
 		cmd = sbp2util_find_command_for_orb(lu, sb->ORB_offset_lo);
 	if (cmd) {
-		dma_sync_single_for_cpu(hi->host->device.parent,
-					cmd->command_orb_dma,
-					sizeof(struct sbp2_command_orb),
-					DMA_TO_DEVICE);
-		dma_sync_single_for_cpu(hi->host->device.parent, cmd->sge_dma,
-					sizeof(cmd->scatter_gather_element),
-					DMA_TO_DEVICE);
 		/* Grab SCSI command pointers and check status. */
 		/*
 		 * FIXME: If the src field in the status is 1, the ORB DMA must

-- 
Stefan Richter
-=====-==--- =--- -=---
http://arcgraph.de/sr/

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