Skip to contentSkip to conversation

aic7xxx driver. Restrict DMA to 32bit for 29320LPE Adaptec SCSI controller

PATCH In review Anil K. Ravindranath 2 participants 4 messages Jun 30, 2007 – Sep 21, 2007 1 message not in the archive SCSI

lore
Share & tools
lore

Anil K. Ravindranath

author
#0 lore raw

PATCH 1/1 aic7xxx driver. Restrict DMA to 32bit for 29320LPE Adaptec SCSI controller

Subject: [PATCH] aic7xxx driver. Restrict DMA to 32bit for 29320LPE Adaptec SCSI controller

Contribution:

Anil Ravindranath <[email protected]>

Issue:

Data Bursts that cross from 32- to 64-Bit address space have incorrect address for 29320LPE. This leads to potential data corruption.

Fix:

Restrict DMA to 32bit so that it does not cross 4GB boundary.

Change Log:

Restrict DMA to 32bit for 29320LPE so that it does not cross 4GB boundary

Patch: apply to scsi-misc-2.6.git development tree

Signed off By: Anil Ravindranath <[email protected]>

diff -urN a/drivers/scsi/aic7xxx/aic79xx_osm_pci.c b/drivers/scsi/aic7xxx/aic79xx_osm_pci.c
--- a/drivers/scsi/aic7xxx/aic79xx_osm_pci.c 2007-06-30
05:24:08.000000000 -0700
+++ b/drivers/scsi/aic7xxx/aic79xx_osm_pci.c 2007-06-30
05:25:40.000000000 -0700
@@ -161,7 +161,10 @@

        }
        pci_set_master(pdev);

- if (sizeof(dma_addr_t) > 4) {
+ /*
+ * Restrict DMA to 32bit for 29320LPE
+ */
+ if ((sizeof(dma_addr_t) > 4) && (entry->full_id !=

ID_AHA_29320LPE)) {
                const u64 required_mask = dma_get_required_mask(dev);

                if (required_mask > DMA_39BIT_MASK &&

diffstat output:

aic79xx_osm_pci.c | 5 ++++-

 1 files changed, 4 insertions(+), 1 deletion(-)

With regards,
Anil

author
#1 lore raw

Hi,

We have not heard any comments or inputs on this patch.

With regards,
Anil

Quoted 54 lines · Anil K. Ravindranath

Subject: [PATCH] aic7xxx driver. Restrict DMA to 32bit for 29320LPE Adaptec SCSI controller

Contribution:

Anil Ravindranath <[email protected]>

Issue:

Data Bursts that cross from 32- to 64-Bit address space have incorrect address for 29320LPE. This leads to potential data corruption.

Fix:

Restrict DMA to 32bit so that it does not cross 4GB boundary.

Change Log:

Restrict DMA to 32bit for 29320LPE so that it does not cross 4GB boundary

Patch: apply to scsi-misc-2.6.git development tree

Signed off By: Anil Ravindranath <[email protected]>

diff -urN a/drivers/scsi/aic7xxx/aic79xx_osm_pci.c b/drivers/scsi/aic7xxx/aic79xx_osm_pci.c
--- a/drivers/scsi/aic7xxx/aic79xx_osm_pci.c 2007-06-30
05:24:08.000000000 -0700
+++ b/drivers/scsi/aic7xxx/aic79xx_osm_pci.c 2007-06-30
05:25:40.000000000 -0700

(quoted diff) +4 -1
@@ -161,7 +161,10 @@
        }
        pci_set_master(pdev);
 
-       if (sizeof(dma_addr_t) > 4) {
+       /*
+        * Restrict DMA to 32bit for 29320LPE
+        */
+       if ((sizeof(dma_addr_t) > 4) && (entry->full_id !=
 ID_AHA_29320LPE)) {
                const u64 required_mask = dma_get_required_mask(dev);
 

                if (required_mask > DMA_39BIT_MASK &&

diffstat output:

aic79xx_osm_pci.c | 5 ++++-

 1 files changed, 4 insertions(+), 1 deletion(-)

With regards,
Anil

#2 lore raw
Quoted 19 lines · Anil K. Ravindranath

Hi,

We have not heard any comments or inputs on this patch.

With regards,
Anil

Quoted 11 lines · Anil K. Ravindranath

Subject: [PATCH] aic7xxx driver. Restrict DMA to 32bit for 29320LPE Adaptec SCSI controller

Contribution:

Anil Ravindranath <[email protected]>

Issue:

Data Bursts that cross from 32- to 64-Bit address space have incorrect address for 29320LPE. This leads to potential data corruption.

Where do you think you see this happening? The block layer has a dma_boundary parameter (basically a mask which it refuses to allow dma to cross). By default this is set to 4GB (because a lot of PCI cards have difficulty going from non-DAC to DAC). The aic79xx driver does nothing to alter this, so you shouldn't be seeing any DMA segments crossing the 4GB boundary.

James

A message that is not in the archive (sent off-list or not yet received): [email protected]

#4 lore raw

please don't drop linux-scsi ... just because no-one else has asked the question doesn't mean they're not interested in the answer. Having the answer in the list means that search tools can find it.

Quoted 4 lines · Anil K. Ravindranath

Oh I see. I looked into the scsi_host_alloc(), now I see this.Thanks. By setting a dma_boundary to 4G, does it mean the kernel(in block) is ensuring that a DMA segment will not cross this 4G boundary. I mean a DMA segment will not be split at 4G boundary.

Yes, that's exactly what it means. Primarily, as I said, because PCI bridges can't necessarily span non-DAC to DAC in a single DMA transfer.

James

Quoted 36 lines

With regards,
Anil

Quoted 31 lines · James Bottomley
Quoted 19 lines · Anil K. Ravindranath

Hi,

We have not heard any comments or inputs on this patch.

With regards,
Anil

Quoted 11 lines · Anil K. Ravindranath

Subject: [PATCH] aic7xxx driver. Restrict DMA to 32bit for 29320LPE Adaptec SCSI controller

Contribution:

Anil Ravindranath <[email protected]>

Issue:

Data Bursts that cross from 32- to 64-Bit address space have incorrect address for 29320LPE. This leads to potential data corruption.

Where do you think you see this happening? The block layer has a dma_boundary parameter (basically a mask which it refuses to allow dma to cross). By default this is set to 4GB (because a lot of PCI cards have difficulty going from non-DAC to DAC). The aic79xx driver does nothing to alter this, so you shouldn't be seeing any DMA segments crossing the 4GB boundary.

James