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From 0dd4fe03156810ab212427474240ea66e35e49f7 Mon Sep 17 00:00:00 2001 |
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From: Sasha Levin <sashal@kernel.org> |
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Date: Wed, 24 Aug 2022 22:34:49 +0200 |
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Subject: net: stmmac: work around sporadic tx issue on link-up |
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|
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From: Heiner Kallweit <hkallweit1@gmail.com> |
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|
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[ Upstream commit a3a57bf07de23fe1ff779e0fdf710aa581c3ff73 ] |
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|
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This is a follow-up to the discussion in [0]. It seems to me that |
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at least the IP version used on Amlogic SoC's sometimes has a problem |
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if register MAC_CTRL_REG is written whilst the chip is still processing |
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a previous write. But that's just a guess. |
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Adding a delay between two writes to this register helps, but we can |
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also simply omit the offending second write. This patch uses the second |
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approach and is based on a suggestion from Qi Duan. |
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Benefit of this approach is that we can save few register writes, also |
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on not affected chip versions. |
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|
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[0] https://www.spinics.net/lists/netdev/msg831526.html |
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|
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Fixes: bfab27a146ed ("stmmac: add the experimental PCI support") |
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Suggested-by: Qi Duan <qi.duan@amlogic.com> |
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Suggested-by: Jerome Brunet <jbrunet@baylibre.com> |
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Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> |
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Link: https://lore.kernel.org/r/e99857ce-bd90-5093-ca8c-8cd480b5a0a2@gmail.com |
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Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Signed-off-by: Sasha Levin <sashal@kernel.org> |
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--- |
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drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c | 8 ++++++-- |
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drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 9 +++++---- |
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2 files changed, 11 insertions(+), 6 deletions(-) |
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|
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diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c b/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c |
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index caa4bfc4c1d62..9b6138b117766 100644 |
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--- a/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c |
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+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c |
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@@ -258,14 +258,18 @@ EXPORT_SYMBOL_GPL(stmmac_set_mac_addr); |
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/* Enable disable MAC RX/TX */ |
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void stmmac_set_mac(void __iomem *ioaddr, bool enable) |
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{ |
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- u32 value = readl(ioaddr + MAC_CTRL_REG); |
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+ u32 old_val, value; |
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+ |
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+ old_val = readl(ioaddr + MAC_CTRL_REG); |
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+ value = old_val; |
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|
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if (enable) |
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value |= MAC_ENABLE_RX | MAC_ENABLE_TX; |
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else |
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value &= ~(MAC_ENABLE_TX | MAC_ENABLE_RX); |
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|
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- writel(value, ioaddr + MAC_CTRL_REG); |
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+ if (value != old_val) |
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+ writel(value, ioaddr + MAC_CTRL_REG); |
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} |
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|
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void stmmac_get_mac_addr(void __iomem *ioaddr, unsigned char *addr, |
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diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |
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index c5f33630e7718..78f11dabca056 100644 |
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--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |
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+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |
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@@ -983,10 +983,10 @@ static void stmmac_mac_link_up(struct phylink_config *config, |
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bool tx_pause, bool rx_pause) |
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{ |
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struct stmmac_priv *priv = netdev_priv(to_net_dev(config->dev)); |
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- u32 ctrl; |
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+ u32 old_ctrl, ctrl; |
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|
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- ctrl = readl(priv->ioaddr + MAC_CTRL_REG); |
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- ctrl &= ~priv->hw->link.speed_mask; |
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+ old_ctrl = readl(priv->ioaddr + MAC_CTRL_REG); |
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+ ctrl = old_ctrl & ~priv->hw->link.speed_mask; |
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|
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if (interface == PHY_INTERFACE_MODE_USXGMII) { |
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switch (speed) { |
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@@ -1061,7 +1061,8 @@ static void stmmac_mac_link_up(struct phylink_config *config, |
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if (tx_pause && rx_pause) |
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stmmac_mac_flow_ctrl(priv, duplex); |
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|
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- writel(ctrl, priv->ioaddr + MAC_CTRL_REG); |
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+ if (ctrl != old_ctrl) |
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+ writel(ctrl, priv->ioaddr + MAC_CTRL_REG); |
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|
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stmmac_mac_set(priv, priv->ioaddr, true); |
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if (phy && priv->dma_cap.eee) { |
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-- |
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2.35.1 |
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