[SCSI] stex: add small dma buffer support

The controllers of st_seq and st_vsc type can work
if only small dma buffer is available, with a reduced
firmware feature set. Add support for this case.

Signed-off-by: Ed Lin <ed.lin@promise.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 20 insertions, 5 deletions

diff --git a/drivers/scsi/stex.c b/drivers/scsi/stex.c
index 09fa8861fc58..af5bafcccf1f 100644
--- a/drivers/scsi/stex.c
+++ b/drivers/scsi/stex.c
@@ -160,6 +160,7 @@ enum {
         INQUIRY_EVPD                            = 0x01,
 
         ST_ADDITIONAL_MEM                       = 0x200000,
+        ST_ADDITIONAL_MEM_MIN                   = 0x80000,
 };
 
 struct st_sgitem {
@@ -1001,7 +1002,7 @@ static int stex_common_handshake(struct st_hba *hba)
         h->partner_type = HMU_PARTNER_TYPE;
         if (hba->extra_offset) {
                 h->extra_offset = cpu_to_le32(hba->extra_offset);
-                h->extra_size = cpu_to_le32(ST_ADDITIONAL_MEM);
+                h->extra_size = cpu_to_le32(hba->dma_size - hba->extra_offset);
         } else
                 h->extra_offset = h->extra_size = 0;
 
@@ -1528,10 +1529,24 @@ stex_probe(struct pci_dev *pdev, const struct pci_device_id *id)
         hba->dma_mem = dma_alloc_coherent(&pdev->dev,
                 hba->dma_size, &hba->dma_handle, GFP_KERNEL);
         if (!hba->dma_mem) {
-                err = -ENOMEM;
-                printk(KERN_ERR DRV_NAME "(%s): dma mem alloc failed\n",
-                        pci_name(pdev));
-                goto out_iounmap;
+                /* Retry minimum coherent mapping for st_seq and st_vsc */
+                if (hba->cardtype == st_seq ||
+                    (hba->cardtype == st_vsc && (pdev->subsystem_device & 1))) {
+                        printk(KERN_WARNING DRV_NAME
+                                "(%s): allocating min buffer for controller\n",
+                                pci_name(pdev));
+                        hba->dma_size = hba->extra_offset
+                                + ST_ADDITIONAL_MEM_MIN;
+                        hba->dma_mem = dma_alloc_coherent(&pdev->dev,
+                                hba->dma_size, &hba->dma_handle, GFP_KERNEL);
+                }
+
+                if (!hba->dma_mem) {
+                        err = -ENOMEM;
+                        printk(KERN_ERR DRV_NAME "(%s): dma mem alloc failed\n",
+                                pci_name(pdev));
+                        goto out_iounmap;
+                }
         }
 
         hba->ccb = kcalloc(ci->rq_count, sizeof(struct st_ccb), GFP_KERNEL);