netdev - [PATCH] driver: ethernet: stmmac: remove the redundant clock disable action

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Message-Id: <20211106104401.10846-1-Meng.Li@windriver.com>
Date:   Sat,  6 Nov 2021 18:44:01 +0800
From:   Meng Li <Meng.Li@...driver.com>
To:     stable@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        mcoquelin.stm32@...il.com
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        meng.li@...driver.com
Subject: [PATCH] driver: ethernet: stmmac: remove the redundant clock disable action

When run below command to remove ethernet driver on
stratix10 platform, there will be warning trace as below:

$ cd /sys/class/net/etha01/device/driver
$ echo ff800000.ethernet > unbind

WARNING: CPU: 3 PID: 386 at drivers/clk/clk.c:810 clk_core_unprepare+0x114/0x274
Modules linked in: sch_fq_codel
CPU: 3 PID: 386 Comm: sh Tainted: G        W         5.10.74-yocto-standard #1
Hardware name: SoCFPGA Stratix 10 SoCDK (DT)
pstate: 00000005 (nzcv daif -PAN -UAO -TCO BTYPE=--)
pc : clk_core_unprepare+0x114/0x274
lr : clk_core_unprepare+0x114/0x274
sp : ffff800011bdbb10
clk_core_unprepare+0x114/0x274
 clk_unprepare+0x38/0x50
 stmmac_remove_config_dt+0x40/0x80
 stmmac_pltfr_remove+0x64/0x80
 platform_drv_remove+0x38/0x60
 ... ..
 el0_sync_handler+0x1a4/0x1b0
 el0_sync+0x180/0x1c0
This issue is introduced by introducing upstream commit 8f269102baf7
("net: stmmac: disable clocks in stmmac_remove_config_dt()")
Because clock has been disabled in function stmmac_dvr_remove()
It not reasonable the remove clock disable action from function
stmmac_remove_config_dt(), because it is mainly used in probe failed,
and other platform drivers also use this common function. So, remove
stmmac_remove_config_dt() from stmmac_pltfr_remove(), only other
necessary code.

Fixes: 1af3a8e91f1a ("net: stmmac: disable clocks in stmmac_remove_config_dt()")
Signed-off-by: Meng Li <Meng.Li@...driver.com>

---

Some extra comments as below:

1. This patch is only for linux-stable kernel v5.10, so the fixed commit ID is the one
   in linux-stable kernel, not the one in mainline upsteam kernel.

2. I created a patch only to fix the linux-stable kernel v5.10, not submit it to upstream kernel.
   The reason as below:
   In fact, upstream kernel doesn't have this issue any more. Because it has a patch to improve
   the clock management and other 4 patches to fix the 1st patch. Detial patches as below:
   5ec55823438e("net: stmmac: add clocks management for gmac driver")
   30f347ae7cc1("net: stmmac: fix missing unlock on error in stmmac_suspend()")
   b3dcb3127786("net: stmmac: correct clocks enabled in stmmac_vlan_rx_kill_vid()")
   4691ffb18ac9("net: stmmac: fix system hang if change mac address after interface ifdown")
   ab00f3e051e8("net: stmmac: fix issue where clk is being unprepared twice")

   But I think it is a little complex to backport all the 5 patches. Moreover, it may be related
   with other patches and code context mofification.
   Therefore, I create a simple and clear patch to only this issue on linux-stable kernel, v 5.10

---
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 53be8fc1d125..0fb702ce2408 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -706,7 +706,8 @@ int stmmac_pltfr_remove(struct platform_device *pdev)
 	if (plat->exit)
 		plat->exit(pdev, plat->bsp_priv);

-	stmmac_remove_config_dt(pdev, plat);
+	of_node_put(plat->phy_node);
+	of_node_put(plat->mdio_node);

 	return ret;
 }
-- 
2.17.1