[PATCH net v4 1/4] net: mvpp2: sync RX data at the hardware packet offset

[Til Kaiser <mail@tk154.de>]

mvpp2 programs the RX queue packet offset, so hardware writes received
data at dma_addr + MVPP2_SKB_HEADROOM. The current CPU sync starts at
dma_addr and only covers rx_bytes + MVPP2_MH_SIZE bytes, which syncs the
unused headroom and misses the same number of bytes at the packet tail.

On non-coherent DMA systems this can leave the CPU reading stale cache
contents for the end of the received frame.

Use dma_sync_single_range_for_cpu() with MVPP2_SKB_HEADROOM as the range
offset so the sync covers the Marvell header and packet data actually
written by hardware.

Fixes: e1921168bbd4 ("mvpp2: sync only the received frame")
Signed-off-by: Til Kaiser <mail@tk154.de>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index f442b874bb59..92a701f4fe3f 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -3946,9 +3946,10 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi,
 			dma_dir = DMA_FROM_DEVICE;
 		}
 
-		dma_sync_single_for_cpu(dev->dev.parent, dma_addr,
-					rx_bytes + MVPP2_MH_SIZE,
-					dma_dir);
+		dma_sync_single_range_for_cpu(dev->dev.parent, dma_addr,
+					      MVPP2_SKB_HEADROOM,
+					      rx_bytes + MVPP2_MH_SIZE,
+					      dma_dir);
 
 		/* Buffer header not supported */
 		if (rx_status & MVPP2_RXD_BUF_HDR)
-- 
2.54.0