ixgbe: work around for DDP last buffer size

A HW limitation was recently discovered where the last buffer in a DDP offload
cannot be a full buffer size in length. Fix the issue with a work around by
adding another buffer with size = 1.

Signed-off-by: Amir Hanania <amir.hanania@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

2 files changed, 52 insertions, 1 deletions

diff --git a/drivers/net/ixgbe/ixgbe_fcoe.c b/drivers/net/ixgbe/ixgbe_fcoe.c
index 8753980668c7..c54a88274d51 100644
--- a/drivers/net/ixgbe/ixgbe_fcoe.c
+++ b/drivers/net/ixgbe/ixgbe_fcoe.c
@@ -159,7 +159,7 @@ int ixgbe_fcoe_ddp_get(struct net_device *netdev, u16 xid,
         struct scatterlist *sg;
         unsigned int i, j, dmacount;
         unsigned int len;
-        static const unsigned int bufflen = 4096;
+        static const unsigned int bufflen = IXGBE_FCBUFF_MIN;
         unsigned int firstoff = 0;
         unsigned int lastsize;
         unsigned int thisoff = 0;
@@ -254,6 +254,24 @@ int ixgbe_fcoe_ddp_get(struct net_device *netdev, u16 xid,
         /* only the last buffer may have non-full bufflen */
         lastsize = thisoff + thislen;
 
+        /*
+         * lastsize can not be buffer len.
+         * If it is then adding another buffer with lastsize = 1.
+         */
+        if (lastsize == bufflen) {
+                if (j >= IXGBE_BUFFCNT_MAX) {
+                        e_err(drv, "xid=%x:%d,%d,%d:addr=%llx "
+                                "not enough user buffers. We need an extra "
+                                "buffer because lastsize is bufflen.\n",
+                                xid, i, j, dmacount, (u64)addr);
+                        goto out_noddp_free;
+                }
+
+                ddp->udl[j] = (u64)(fcoe->extra_ddp_buffer_dma);
+                j++;
+                lastsize = 1;
+        }
+
         fcbuff = (IXGBE_FCBUFF_4KB << IXGBE_FCBUFF_BUFFSIZE_SHIFT);
         fcbuff |= ((j & 0xff) << IXGBE_FCBUFF_BUFFCNT_SHIFT);
         fcbuff |= (firstoff << IXGBE_FCBUFF_OFFSET_SHIFT);
@@ -532,6 +550,24 @@ void ixgbe_configure_fcoe(struct ixgbe_adapter *adapter)
                         e_err(drv, "failed to allocated FCoE DDP pool\n");
 
                 spin_lock_init(&fcoe->lock);
+
+                /* Extra buffer to be shared by all DDPs for HW work around */
+                fcoe->extra_ddp_buffer = kmalloc(IXGBE_FCBUFF_MIN, GFP_ATOMIC);
+                if (fcoe->extra_ddp_buffer == NULL) {
+                        e_err(drv, "failed to allocated extra DDP buffer\n");
+                        goto out_extra_ddp_buffer_alloc;
+                }
+
+                fcoe->extra_ddp_buffer_dma =
+                        dma_map_single(&adapter->pdev->dev,
+                                       fcoe->extra_ddp_buffer,
+                                       IXGBE_FCBUFF_MIN,
+                                       DMA_FROM_DEVICE);
+                if (dma_mapping_error(&adapter->pdev->dev,
+                                      fcoe->extra_ddp_buffer_dma)) {
+                        e_err(drv, "failed to map extra DDP buffer\n");
+                        goto out_extra_ddp_buffer_dma;
+                }
         }
 
         /* Enable L2 eth type filter for FCoE */
@@ -581,6 +617,14 @@ void ixgbe_configure_fcoe(struct ixgbe_adapter *adapter)
                 }
         }
 #endif
+
+        return;
+
+out_extra_ddp_buffer_dma:
+        kfree(fcoe->extra_ddp_buffer);
+out_extra_ddp_buffer_alloc:
+        pci_pool_destroy(fcoe->pool);
+        fcoe->pool = NULL;
 }
 
 /**
@@ -600,6 +644,11 @@ void ixgbe_cleanup_fcoe(struct ixgbe_adapter *adapter)
         if (fcoe->pool) {
                 for (i = 0; i < IXGBE_FCOE_DDP_MAX; i++)
                         ixgbe_fcoe_ddp_put(adapter->netdev, i);
+                dma_unmap_single(&adapter->pdev->dev,
+                                 fcoe->extra_ddp_buffer_dma,
+                                 IXGBE_FCBUFF_MIN,
+                                 DMA_FROM_DEVICE);
+                kfree(fcoe->extra_ddp_buffer);
                 pci_pool_destroy(fcoe->pool);
                 fcoe->pool = NULL;
         }
diff --git a/drivers/net/ixgbe/ixgbe_fcoe.h b/drivers/net/ixgbe/ixgbe_fcoe.h
index 4bc2c551c8db..65cc8fb14fe7 100644
--- a/drivers/net/ixgbe/ixgbe_fcoe.h
+++ b/drivers/net/ixgbe/ixgbe_fcoe.h
@@ -70,6 +70,8 @@ struct ixgbe_fcoe {
         spinlock_t lock;
         struct pci_pool *pool;
         struct ixgbe_fcoe_ddp ddp[IXGBE_FCOE_DDP_MAX];
+        unsigned char *extra_ddp_buffer;
+        dma_addr_t extra_ddp_buffer_dma;
 };
 
 #endif /* _IXGBE_FCOE_H */