layerscape: add patches-5.4

[openwrt/staging/wigyori.git] / target / linux / layerscape / patches-5.4 / 701-net-0047-sdk_dpaa-update-comments-about-recycling-and-back-po.patch

diff --git a/target/linux/layerscape/patches-5.4/701-net-0047-sdk_dpaa-update-comments-about-recycling-and-back-po.patch b/target/linux/layerscape/patches-5.4/701-net-0047-sdk_dpaa-update-comments-about-recycling-and-back-po.patch
new file mode 100644 (file)
index 0000000..a54dce9
--- /dev/null
+++ b/target/linux/layerscape/patches-5.4/701-net-0047-sdk_dpaa-update-comments-about-recycling-and-back-po.patch
@@ -0,0 +1,67 @@
+From 2d7b6e7daf076b63f461ce9c4ec6022ddc3d15bb Mon Sep 17 00:00:00 2001
+From: Camelia Groza <camelia.groza@nxp.com>
+Date: Mon, 15 Jan 2018 17:42:42 +0200
+Subject: [PATCH] sdk_dpaa: update comments about recycling and back-pointer
+ storage
+
+Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
+---
+ drivers/net/ethernet/freescale/sdk_dpaa/dpaa_eth_sg.c | 18 ++++++++++++++++--
+ 1 file changed, 16 insertions(+), 2 deletions(-)
+
+--- a/drivers/net/ethernet/freescale/sdk_dpaa/dpaa_eth_sg.c
++++ b/drivers/net/ethernet/freescale/sdk_dpaa/dpaa_eth_sg.c
+@@ -121,6 +121,10 @@ static int _dpa_bp_add_8_bufs(const stru
+                       put_page(virt_to_head_page(new_buf));
+                       goto build_skb_failed;
+               }
++
++              /* Store the skb back-pointer before the start of the buffer.
++               * Otherwise it will be overwritten by the FMan.
++               */
+               DPA_WRITE_SKB_PTR(skb, skbh, new_buf, -1);
+ 
+               addr = dma_map_single(dev, new_buf,
+@@ -344,7 +348,10 @@ bool dpa_buf_is_recyclable(struct sk_buf
+        * - buffer address aligned to cacheline bytes
+        * - offset of data from start of buffer no lower than a minimum value
+        * - offset of data from start of buffer no higher than a maximum value
++       * - the skb back-pointer is stored safely
+        */
++
++      /* guarantee both the minimum size and the minimum data offset */
+       new = min(skb_end_pointer(skb) - min_size, skb->data - min_offset);
+ 
+       /* left align to the nearest cacheline */
+@@ -694,6 +701,9 @@ int __hot skb_to_contig_fd(struct dpa_pr
+               dma_dir = DMA_BIDIRECTIONAL;
+               dma_map_size = dpa_bp->size;
+ 
++              /* Store the skb back-pointer before the start of the buffer.
++               * Otherwise it will be overwritten by the FMan.
++               */
+               DPA_WRITE_SKB_PTR(skb, skbh, buffer_start, -1);
+               *offset = skb_headroom(skb) - fd->offset;
+       } else
+@@ -711,7 +721,7 @@ int __hot skb_to_contig_fd(struct dpa_pr
+ 
+               /* The buffer will be Tx-confirmed, but the TxConf cb must
+                * necessarily look at our Tx private data to retrieve the
+-               * skbuff. (In short: can't use DPA_WRITE_SKB_PTR() here.)
++               * skbuff. Store the back-pointer inside the buffer.
+                */
+               DPA_WRITE_SKB_PTR(skb, skbh, buffer_start, 0);
+       }
+@@ -975,7 +985,11 @@ int __hot skb_to_sg_fd(struct dpa_priv_s
+       fd->length20 = skb->len;
+       fd->offset = priv->tx_headroom;
+ 
+-      /* DMA map the SGT page */
++      /* DMA map the SGT page
++       *
++       * It's safe to store the skb back-pointer inside the buffer since
++       * S/G frames are non-recyclable.
++       */
+       DPA_WRITE_SKB_PTR(skb, skbh, sgt_buf, 0);
+       addr = dma_map_single(dpa_bp->dev, sgt_buf,
+                             priv->tx_headroom + sgt_size,