net: thunderx: Optimize RBDR descriptor handling

Receive buffer's physical address or iova will anyway not
go beyond 49bits, since it is the max supported HW address.
As per perf, updating bitfields i.e buf_addr:42 in RBDR
descriptor entry consumes lots of cpu cycles, hence changed
it to a 64bit field with alignment requirements taken care of.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 5 insertions, 13 deletions

diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
index 12f9709bb180..dfc85a169127 100644
--- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
@@ -257,7 +257,7 @@ static int  nicvf_init_rbdr(struct nicvf *nic, struct rbdr *rbdr,
                 }
 
                 desc = GET_RBDR_DESC(rbdr, idx);
-                desc->buf_addr = (u64)rbuf >> NICVF_RCV_BUF_ALIGN;
+                desc->buf_addr = (u64)rbuf & ~(NICVF_RCV_BUF_ALIGN_BYTES - 1);
         }
 
         nicvf_get_page(nic);
@@ -286,7 +286,7 @@ static void nicvf_free_rbdr(struct nicvf *nic, struct rbdr *rbdr)
         /* Release page references */
         while (head != tail) {
                 desc = GET_RBDR_DESC(rbdr, head);
-                buf_addr = ((u64)desc->buf_addr) << NICVF_RCV_BUF_ALIGN;
+                buf_addr = desc->buf_addr;
                 phys_addr = nicvf_iova_to_phys(nic, buf_addr);
                 dma_unmap_page_attrs(&nic->pdev->dev, buf_addr, RCV_FRAG_LEN,
                                      DMA_FROM_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
@@ -297,7 +297,7 @@ static void nicvf_free_rbdr(struct nicvf *nic, struct rbdr *rbdr)
         }
         /* Release buffer of tail desc */
         desc = GET_RBDR_DESC(rbdr, tail);
-        buf_addr = ((u64)desc->buf_addr) << NICVF_RCV_BUF_ALIGN;
+        buf_addr = desc->buf_addr;
         phys_addr = nicvf_iova_to_phys(nic, buf_addr);
         dma_unmap_page_attrs(&nic->pdev->dev, buf_addr, RCV_FRAG_LEN,
                              DMA_FROM_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
@@ -364,7 +364,7 @@ refill:
                         break;
 
                 desc = GET_RBDR_DESC(rbdr, tail);
-                desc->buf_addr = (u64)rbuf >> NICVF_RCV_BUF_ALIGN;
+                desc->buf_addr = (u64)rbuf & ~(NICVF_RCV_BUF_ALIGN_BYTES - 1);
                 refill_rb_cnt--;
                 new_rb++;
         }
diff --git a/drivers/net/ethernet/cavium/thunder/q_struct.h b/drivers/net/ethernet/cavium/thunder/q_struct.h
index f36347237a54..e47205aa87ea 100644
--- a/drivers/net/ethernet/cavium/thunder/q_struct.h
+++ b/drivers/net/ethernet/cavium/thunder/q_struct.h
@@ -359,15 +359,7 @@ union cq_desc_t {
 };
 
 struct rbdr_entry_t {
-#if defined(__BIG_ENDIAN_BITFIELD)
-        u64   rsvd0:15;
-        u64   buf_addr:42;
-        u64   cache_align:7;
-#elif defined(__LITTLE_ENDIAN_BITFIELD)
-        u64   cache_align:7;
-        u64   buf_addr:42;
-        u64   rsvd0:15;
-#endif
+        u64   buf_addr;
 };
 
 /* TCP reassembly context */