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Date:   Mon, 28 Nov 2022 13:05:09 -0800
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Subject: Re: [v2][PATCH 1/1] net: phy: Add link between phy dev and mac dev
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To:     Xiaolei Wang <xiaolei.wang@windriver.com>, andrew@lunn.ch,
        hkallweit1@gmail.com, linux@armlinux.org.uk, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20221125041206.1883833-1-xiaolei.wang@windriver.com>
 <20221125041206.1883833-2-xiaolei.wang@windriver.com>
From:   Florian Fainelli <f.fainelli@gmail.com>
In-Reply-To: <20221125041206.1883833-2-xiaolei.wang@windriver.com>
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On 11/24/22 20:12, Xiaolei Wang wrote:
> If the external phy used by current mac interface is
> managed by another mac interface, it means that this
> network port cannot work independently, especially
> when the system suspend and resume, the following
> trace may appear, so we should create a device link
> between phy dev and mac dev.
> 
>    WARNING: CPU: 0 PID: 24 at drivers/net/phy/phy.c:983 phy_error+0x20/0x68
>    Modules linked in:
>    CPU: 0 PID: 24 Comm: kworker/0:2 Not tainted 6.1.0-rc3-00011-g5aaef24b5c6d-dirty #34
>    Hardware name: Freescale i.MX6 SoloX (Device Tree)
>    Workqueue: events_power_efficient phy_state_machine
>    unwind_backtrace from show_stack+0x10/0x14
>    show_stack from dump_stack_lvl+0x68/0x90
>    dump_stack_lvl from __warn+0xb4/0x24c
>    __warn from warn_slowpath_fmt+0x5c/0xd8
>    warn_slowpath_fmt from phy_error+0x20/0x68
>    phy_error from phy_state_machine+0x22c/0x23c
>    phy_state_machine from process_one_work+0x288/0x744
>    process_one_work from worker_thread+0x3c/0x500
>    worker_thread from kthread+0xf0/0x114
>    kthread from ret_from_fork+0x14/0x28
>    Exception stack(0xf0951fb0 to 0xf0951ff8)
> 
> Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>

Tested with bcmgenet and bcmsysport/bcm_sf2:

- suspend/resume using rtcwake w/ Wake-on-LAN disabled
- suspend/resume using rtcwale w/ Wake-on-LAN enabled
- reboot -f (which does exercise the shutdown path which has ties with 
device_links)
- binding/unbinding PHY driver

There was no change to the ordering for GENET, however there was a 
change of ordering for the DSA (bcmsysport/bcm_sf2) combination but it 
seemed to make more sense the way it was, in that we suspended the 
switch first and later the Ethernet controller attached to the switch.

Thanks for your patience.
-- 
Florian