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

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Message-ID: <298c045a-5438-6761-46d8-c46c57989812@gmail.com>
Date:   Thu, 13 Apr 2023 10:15:55 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Jacob Keller <jacob.e.keller@...el.com>,
        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 4/13/23 10:07, Jacob Keller wrote:
> 
> 
> 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/

Unfortunately both still lack a proper Fixes: tag, and this is bug fix.
-- 
Florian