[PATCH] driver: net: ethernet: mtk_star_emac: fix suspend/resume issue

[PATCH] driver: net: ethernet: mtk_star_emac: fix suspend/resume issue

[Macpaul Lin]

From: Yanqing Wang <ot_yanqing.wang@mediatek.com>

Identify the cause of the suspend/resume hang: netif_carrier_off()
is called during link state changes and becomes stuck while
executing linkwatch_work().

To resolve this issue, call netif_device_detach() during the Ethernet
suspend process to temporarily detach the network device from the
kernel and prevent the suspend/resume hang.

Fixes: 8c7bd5a454ff ("net: ethernet: mtk-star-emac: new driver")
Signed-off-by: Yanqing Wang <ot_yanqing.wang@mediatek.com>
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Signed-off-by: Biao Huang <biao.huang@mediatek.com>
---
 drivers/net/ethernet/mediatek/mtk_star_emac.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/mediatek/mtk_star_emac.c b/drivers/net/ethernet/mediatek/mtk_star_emac.c
index b175119a6a7d..b83886a41121 100644
--- a/drivers/net/ethernet/mediatek/mtk_star_emac.c
+++ b/drivers/net/ethernet/mediatek/mtk_star_emac.c
@@ -1463,6 +1463,8 @@ static __maybe_unused int mtk_star_suspend(struct device *dev)
 	if (netif_running(ndev))
 		mtk_star_disable(ndev);
 
+	netif_device_detach(ndev);
+
 	clk_bulk_disable_unprepare(MTK_STAR_NCLKS, priv->clks);
 
 	return 0;
@@ -1487,6 +1489,8 @@ static __maybe_unused int mtk_star_resume(struct device *dev)
 			clk_bulk_disable_unprepare(MTK_STAR_NCLKS, priv->clks);
 	}
 
+	netif_device_attach(ndev);
+
 	return ret;
 }
 
-- 
2.45.2

Re: [PATCH] driver: net: ethernet: mtk_star_emac: fix suspend/resume issue

[kernel test robot]

Hi,

Thanks for your patch.

FYI: kernel test robot notices the stable kernel rule is not satisfied.

The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-1

Rule: add the tag "Cc: stable@vger.kernel.org" in the sign-off area to have the patch automatically included in the stable tree.
Subject: [PATCH] driver: net: ethernet: mtk_star_emac: fix suspend/resume issue
Link: https://lore.kernel.org/stable/20250528075351.593068-1-macpaul.lin%40mediatek.com

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Re: [PATCH] driver: net: ethernet: mtk_star_emac: fix suspend/resume issue

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Wed, 28 May 2025 15:53:51 +0800 you wrote:
> From: Yanqing Wang <ot_yanqing.wang@mediatek.com>
> 
> Identify the cause of the suspend/resume hang: netif_carrier_off()
> is called during link state changes and becomes stuck while
> executing linkwatch_work().
> 
> To resolve this issue, call netif_device_detach() during the Ethernet
> suspend process to temporarily detach the network device from the
> kernel and prevent the suspend/resume hang.
> 
> [...]

Here is the summary with links:
  - driver: net: ethernet: mtk_star_emac: fix suspend/resume issue
    https://git.kernel.org/netdev/net/c/ba99c627aac8

You are awesome, thank you!
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