[PATCH net-next v4] net: stmmac:fix system hang when setting up tag_8021q VLAN for DSA ports

[Florian Fainelli]

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 at 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.
-- 
Florian