[openwrt/openwrt] ramips: ethernet: fix to interrupt handling

[LEDE Commits]

hauke pushed a commit to openwrt/openwrt.git, branch openwrt-19.07:
https://git.openwrt.org/7ac454014a11347887323a131415ac7032d53546

commit 7ac454014a11347887323a131415ac7032d53546
Author: NeilBrown <neil at brown.name>
AuthorDate: Tue Oct 29 10:23:28 2019 -0700

    ramips: ethernet: fix to interrupt handling
    
    The current code acknowledged interrupts *after* polling.
    This is the wrong way around, and could cause an interrupt to
    be missed.
    This is not likely to be fatal as another packet, and so another
    interrupt, should come along soon.  But maybe it is causing
    problems, so let's fix it anyway.
    
    Signed-off-by: NeilBrown <neil at brown.name>
    (Note that this matches the upstream driver.)
    Signed-off-by: Rosen Penev <rosenp at gmail.com>
---
 .../files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c    | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index b2c3d32c55..3541b11240 100644
--- a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -876,6 +876,8 @@ static int fe_poll_rx(struct napi_struct *napi, int budget,
 	struct fe_rx_dma *rxd, trxd;
 	int done = 0, pad;
 
+	fe_reg_w32(rx_intr, FE_REG_FE_INT_STATUS);
+
 	if (netdev->features & NETIF_F_RXCSUM)
 		checksum_bit = soc->checksum_bit;
 	else
@@ -968,9 +970,6 @@ release_desc:
 		done++;
 	}
 
-	if (done < budget)
-		fe_reg_w32(rx_intr, FE_REG_FE_INT_STATUS);
-
 	return done;
 }
 
@@ -986,6 +985,8 @@ static int fe_poll_tx(struct fe_priv *priv, int budget, u32 tx_intr,
 	u32 idx, hwidx;
 	struct fe_tx_ring *ring = &priv->tx_ring;
 
+	fe_reg_w32(tx_intr, FE_REG_FE_INT_STATUS);
+
 	idx = ring->tx_free_idx;
 	hwidx = fe_reg_r32(FE_REG_TX_DTX_IDX0);
 
@@ -1009,9 +1010,7 @@ static int fe_poll_tx(struct fe_priv *priv, int budget, u32 tx_intr,
 	if (idx == hwidx) {
 		/* read hw index again make sure no new tx packet */
 		hwidx = fe_reg_r32(FE_REG_TX_DTX_IDX0);
-		if (idx == hwidx)
-			fe_reg_w32(tx_intr, FE_REG_FE_INT_STATUS);
-		else
+		if (idx != hwidx)
 			*tx_again = 1;
 	} else {
 		*tx_again = 1;