Patch "net: ethernet: mtk_eth_soc: fix PPE hanging issue" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: ethernet: mtk_eth_soc: fix PPE hanging issue

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-ethernet-mtk_eth_soc-fix-ppe-hanging-issue.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 3bab6dd090d435dccc60f07ed829cec1ff73ef3e
Author: Daniel Golle <daniel@xxxxxxxxxxxxxx>
Date:   Wed Mar 13 22:50:40 2024 +0000

    net: ethernet: mtk_eth_soc: fix PPE hanging issue
    
    [ Upstream commit ea80e3ed09ab2c2b75724faf5484721753e92c31 ]
    
    A patch to resolve an issue was found in MediaTek's GPL-licensed SDK:
    In the mtk_ppe_stop() function, the PPE scan mode is not disabled before
    disabling the PPE. This can potentially lead to a hang during the process
    of disabling the PPE.
    
    Without this patch, the PPE may experience a hang during the reboot test.
    
    Link: https://git01.mediatek.com/plugins/gitiles/openwrt/feeds/mtk-openwrt-feeds/+/b40da332dfe763932a82f9f62a4709457a15dd6c
    Fixes: ba37b7caf1ed ("net: ethernet: mtk_eth_soc: add support for initializing the PPE")
    Suggested-by: Bc-bocun Chen <bc-bocun.chen@xxxxxxxxxxxx>
    Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ethernet/mediatek/mtk_ppe.c b/drivers/net/ethernet/mediatek/mtk_ppe.c
index 66298e2235c91..5e7b66846791d 100644
--- a/drivers/net/ethernet/mediatek/mtk_ppe.c
+++ b/drivers/net/ethernet/mediatek/mtk_ppe.c
@@ -425,7 +425,7 @@ int mtk_ppe_start(struct mtk_ppe *ppe)
 			 MTK_PPE_KEEPALIVE_DISABLE) |
 	      FIELD_PREP(MTK_PPE_TB_CFG_HASH_MODE, 1) |
 	      FIELD_PREP(MTK_PPE_TB_CFG_SCAN_MODE,
-			 MTK_PPE_SCAN_MODE_KEEPALIVE_AGE) |
+			 MTK_PPE_SCAN_MODE_CHECK_AGE) |
 	      FIELD_PREP(MTK_PPE_TB_CFG_ENTRY_NUM,
 			 MTK_PPE_ENTRIES_SHIFT);
 	ppe_w32(ppe, MTK_PPE_TB_CFG, val);
@@ -493,17 +493,21 @@ int mtk_ppe_stop(struct mtk_ppe *ppe)
 
 	mtk_ppe_cache_enable(ppe, false);
 
-	/* disable offload engine */
-	ppe_clear(ppe, MTK_PPE_GLO_CFG, MTK_PPE_GLO_CFG_EN);
-	ppe_w32(ppe, MTK_PPE_FLOW_CFG, 0);
-
 	/* disable aging */
 	val = MTK_PPE_TB_CFG_AGE_NON_L4 |
 	      MTK_PPE_TB_CFG_AGE_UNBIND |
 	      MTK_PPE_TB_CFG_AGE_TCP |
 	      MTK_PPE_TB_CFG_AGE_UDP |
-	      MTK_PPE_TB_CFG_AGE_TCP_FIN;
+	      MTK_PPE_TB_CFG_AGE_TCP_FIN |
+		  MTK_PPE_TB_CFG_SCAN_MODE;
 	ppe_clear(ppe, MTK_PPE_TB_CFG, val);
 
-	return mtk_ppe_wait_busy(ppe);
+	if (mtk_ppe_wait_busy(ppe))
+		return -ETIMEDOUT;
+
+	/* disable offload engine */
+	ppe_clear(ppe, MTK_PPE_GLO_CFG, MTK_PPE_GLO_CFG_EN);
+	ppe_w32(ppe, MTK_PPE_FLOW_CFG, 0);
+
+	return 0;
 }