From: Heiner Kallweit <hkallweit1@xxxxxxxxx> [ Upstream commit a3a57bf07de23fe1ff779e0fdf710aa581c3ff73 ] This is a follow-up to the discussion in [0]. It seems to me that at least the IP version used on Amlogic SoC's sometimes has a problem if register MAC_CTRL_REG is written whilst the chip is still processing a previous write. But that's just a guess. Adding a delay between two writes to this register helps, but we can also simply omit the offending second write. This patch uses the second approach and is based on a suggestion from Qi Duan. Benefit of this approach is that we can save few register writes, also on not affected chip versions. [0] https://www.spinics.net/lists/netdev/msg831526.html Fixes: bfab27a146ed ("stmmac: add the experimental PCI support") Suggested-by: Qi Duan <qi.duan@xxxxxxxxxxx> Suggested-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx> Link: https://lore.kernel.org/r/e99857ce-bd90-5093-ca8c-8cd480b5a0a2@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c | 8 ++++++-- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 9 +++++---- 2 files changed, 11 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c b/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c index d1c31200bb911..01d0a14f67520 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c @@ -258,14 +258,18 @@ EXPORT_SYMBOL_GPL(stmmac_set_mac_addr); /* Enable disable MAC RX/TX */ void stmmac_set_mac(void __iomem *ioaddr, bool enable) { - u32 value = readl(ioaddr + MAC_CTRL_REG); + u32 old_val, value; + + old_val = readl(ioaddr + MAC_CTRL_REG); + value = old_val; if (enable) value |= MAC_ENABLE_RX | MAC_ENABLE_TX; else value &= ~(MAC_ENABLE_TX | MAC_ENABLE_RX); - writel(value, ioaddr + MAC_CTRL_REG); + if (value != old_val) + writel(value, ioaddr + MAC_CTRL_REG); } void stmmac_get_mac_addr(void __iomem *ioaddr, unsigned char *addr, diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index b4f83c8655684..2569673559df3 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -1083,10 +1083,10 @@ static void stmmac_mac_link_up(struct phylink_config *config, bool tx_pause, bool rx_pause) { struct stmmac_priv *priv = netdev_priv(to_net_dev(config->dev)); - u32 ctrl; + u32 old_ctrl, ctrl; - ctrl = readl(priv->ioaddr + MAC_CTRL_REG); - ctrl &= ~priv->hw->link.speed_mask; + old_ctrl = readl(priv->ioaddr + MAC_CTRL_REG); + ctrl = old_ctrl & ~priv->hw->link.speed_mask; if (interface == PHY_INTERFACE_MODE_USXGMII) { switch (speed) { @@ -1161,7 +1161,8 @@ static void stmmac_mac_link_up(struct phylink_config *config, if (tx_pause && rx_pause) stmmac_mac_flow_ctrl(priv, duplex); - writel(ctrl, priv->ioaddr + MAC_CTRL_REG); + if (ctrl != old_ctrl) + writel(ctrl, priv->ioaddr + MAC_CTRL_REG); stmmac_mac_set(priv, priv->ioaddr, true); if (phy && priv->dma_cap.eee) { -- 2.35.1
