linux-kernel - Re: [PATCH net-next v4] net: stmmac:fix system hang when setting up tag

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Date:   Thu, 13 Apr 2023 10:07:37 -0700
From:   Jacob Keller <jacob.e.keller@...el.com>
To:     Yan Wang <rk.code@...look.com>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <pabeni@...hat.com>, <kuba@...nel.org>,
        <mcoquelin.stm32@...il.com>
CC:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "open list:STMMAC ETHERNET DRIVER" <netdev@...r.kernel.org>,
        "moderated list:ARM/STM32 ARCHITECTURE" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "moderated list:ARM/STM32 ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v4] net: stmmac:fix system hang when setting up
 tag_8021q VLAN for DSA ports



On 4/13/2023 8:06 AM, Yan Wang wrote:
> The system hang because of dsa_tag_8021q_port_setup()->
> 				stmmac_vlan_rx_add_vid().
> 
> I found in stmmac_drv_probe() that cailing pm_runtime_put()
> disabled the clock.
> 
> First, when the kernel is compiled with CONFIG_PM=y,The stmmac's
> resume/suspend is active.
> 
> Secondly,stmmac as DSA master,the dsa_tag_8021q_port_setup() function
> will callback stmmac_vlan_rx_add_vid when DSA dirver starts. However,
> The system is hanged for the stmmac_vlan_rx_add_vid() accesses its
> registers after stmmac's clock is closed.
> 
> I would suggest adding the pm_runtime_resume_and_get() to the
> stmmac_vlan_rx_add_vid().This guarantees that resuming clock output
> while in use.
> 
> Signed-off-by: Yan Wang <rk.code@...look.com>

This looks identical to the net fix you posted at [1]. I don't think we
need both?

[1]:
https://lore.kernel.org/netdev/KL1PR01MB5448020DE191340AE64530B0E6989@KL1PR01MB5448.apcprd01.prod.exchangelabs.com/