[PATCH v3 08/12] net: ethernet: mtk_eth_soc: fix RX data corruption issue

From: Daniel Golle
Date: Thu Feb 09 2023 - 18:35:55 EST


Also set bit 12 when setting up MAC MCR, as MediaTek SDK did the same
change stating:
"If without this patch, kernel might receive invalid packets that are
corrupted by GMAC."[1]
Unfortunately the meaning of bit 12 is not documented in datasheets or
vendor code.

[1]: https://git01.mediatek.com/plugins/gitiles/openwrt/feeds/mtk-openwrt-feeds/+/d8a2975939a12686c4a95c40db21efdc3f821f63
Tested-by: Bjørn Mork <bjorn@xxxxxxx>
Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>
---
drivers/net/ethernet/mediatek/mtk_eth_soc.c | 2 +-
drivers/net/ethernet/mediatek/mtk_eth_soc.h | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 030d87c42bd4..fa61eefe0a61 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -615,7 +615,7 @@ static int mtk_mac_finish(struct phylink_config *config, unsigned int mode,
/* Setup gmac */
mcr_cur = mtk_r32(mac->hw, MTK_MAC_MCR(mac->id));
mcr_new = mcr_cur;
- mcr_new |= MAC_MCR_IPG_CFG | MAC_MCR_FORCE_MODE |
+ mcr_new |= MAC_MCR_IPG_CFG | MAC_MCR_BIT_12 | MAC_MCR_FORCE_MODE |
MAC_MCR_BACKOFF_EN | MAC_MCR_BACKPR_EN | MAC_MCR_FORCE_LINK;

/* Only update control register when needed! */
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
index 142def8629c8..084d07c96c04 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -404,6 +404,7 @@
#define MAC_MCR_FORCE_MODE BIT(15)
#define MAC_MCR_TX_EN BIT(14)
#define MAC_MCR_RX_EN BIT(13)
+#define MAC_MCR_BIT_12 BIT(12)
#define MAC_MCR_BACKOFF_EN BIT(9)
#define MAC_MCR_BACKPR_EN BIT(8)
#define MAC_MCR_FORCE_RX_FC BIT(5)
--
2.39.1