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Date:   Thu, 13 Apr 2023 10:31:25 -0700
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Subject: Re: [PATCH net-next v4] net: stmmac:fix system hang when setting up
 tag_8021q VLAN for DSA ports
Content-Language: en-US
To:     Florian Fainelli <f.fainelli@gmail.com>,
        Yan Wang <rk.code@outlook.com>, <davem@davemloft.net>,
        <edumazet@google.com>, <pabeni@redhat.com>, <kuba@kernel.org>,
        <mcoquelin.stm32@gmail.com>
CC:     Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        "open list:STMMAC ETHERNET DRIVER" <netdev@vger.kernel.org>,
        "moderated list:ARM/STM32 ARCHITECTURE" 
        <linux-stm32@st-md-mailman.stormreply.com>,
        "moderated list:ARM/STM32 ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>
References: <KL1PR01MB5448C7BF5A7AAC1CBCD5C36AE6989@KL1PR01MB5448.apcprd01.prod.exchangelabs.com>
 <01ef9d4f-d2dc-d584-4733-798cffda49a1@intel.com>
 <298c045a-5438-6761-46d8-c46c57989812@gmail.com>
From:   Jacob Keller <jacob.e.keller@intel.com>
In-Reply-To: <298c045a-5438-6761-46d8-c46c57989812@gmail.com>
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On 4/13/2023 10:15 AM, Florian Fainelli wrote:
> 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@outlook.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.

Good point. Yan, please identify the appropriate fixes tag and send a v2
of the net fix.

Thanks,
Jake