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Date:   Thu, 23 Jun 2022 08:36:49 +0200
From:   Oleksij Rempel <o.rempel@pengutronix.de>
To:     Anton Lundin <glance@acc.umu.se>
Cc:     "David S. Miller" <davem@davemloft.net>,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        netdev@vger.kernel.org
Subject: Re: [REGRESSION] AX88772 card booted without cable can't receive
Message-ID: <20220623063649.GD23685@pengutronix.de>
References: <20220622141638.GE930160@montezuma.acc.umu.se>
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Hi Anton,

Thank you for your report! I'll take a look on it ASAP.

Regards,
Oleksij

On Wed, Jun 22, 2022 at 04:16:38PM +0200, Anton Lundin wrote:
> Hi.
> 
> I've found a issue with a Dlink usb ether adapter, that can't receive
> anything until it self transmits if it's plugged in while booting, and
> doesn't have link.
> 
> Later when a cable is attached, link is detected but nothing is received
> either by daemons listening to ip address on that interface, or seen
> with tcpdump.
> 
> The dongle is a:
> D-Link Corp. DUB-E100 Fast Ethernet Adapter(rev.C1) [ASIX AX88772]
> 
> And it's detected at boot as:
> libphy: Asix MDIO Bus: probed
> Asix Electronics AX88772C usb-003:004:10: attached PHY driver (mii_bus:phy_addr=usb-003:004:10, irq=POLL)
> asix 3-10.4:1.0 eth1: register 'asix' at usb-0000:00:14.0-10.4, ASIX AX88772 USB 2.0 Ethernet, <masked-mac>
> usbcore: registered new interface driver asix
> 
> 
> While in this state, the hardware starts sending pause frames to the
> network when it has recived a couple of frames, and they look like:
> 0000   01 80 c2 00 00 01 00 00 00 00 00 00 88 08 00 01
> 0010   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0020   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0030   00 00 00 00 00 00 00 00 00 00 00 00
> 
> 0000   01 80 c2 00 00 01 00 00 00 00 00 00 88 08 00 01
> 0010   ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0020   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0030   00 00 00 00 00 00 00 00 00 00 00 00
> 
> And these two frames are repeated every couple of seconds.
> 
> The card wakes up when something triggers a transmit on that card, and
> then starts receiving traffic as normal.
> 
> I've bisected this issue down to:
> "net: usb: asix: ax88772: add phylib support" (e532a096be0e)
> 
> 
> Reverting that makes the interface work as normal, even if the machine
> boots without a cable plugged in.
> 
> Another issue found with exactly the same patch is that if it's loaded
> as a module, then unloaded and loaded again, it fails to initialize the
> card with:
> 
> sysfs: cannot create duplicate filename '/devices/virtual/mdio_bus/usb-003:004'
> CPU: 0 PID: 3733 Comm: modprobe Tainted: G           O      5.15.10-core_64_preempt #3
> Hardware name:  <masked-hardware-name>
> Call Trace:
>  <TASK>
>  ? dump_stack_lvl+0x34/0x44
>  ? sysfs_warn_dup.cold+0x17/0x24
>  ? sysfs_create_dir_ns+0xbc/0xd0
>  ? kobject_add_internal+0xa6/0x260
>  ? kobject_add+0x7e/0xb0
>  ? preempt_count_add+0x68/0xa0
>  ? device_add+0x10f/0x8d0
>  ? dev_set_name+0x53/0x70
>  ? __mdiobus_register+0xc2/0x350
>  ? __devm_mdiobus_register+0x64/0xb0
>  ? ax88772_bind+0x22a/0x340 [asix]
>  ? usbnet_probe+0x346/0x870
>  ? usb_match_dynamic_id+0x8f/0xa0
>  ? usb_probe_interface+0x9b/0x150
>  ? really_probe.part.0+0x237/0x280
>  ? __driver_probe_device+0x8c/0xd0
>  ? driver_probe_device+0x1e/0xe0
>  ? __driver_attach+0xa8/0x170
>  ? __device_attach_driver+0xe0/0xe0
>  ? bus_for_each_dev+0x77/0xc0
>  ? bus_add_driver+0x10b/0x1c0
>  ? driver_register+0x8b/0xe0
>  ? usb_register_driver+0x84/0x120
>  ? 0xffffffffc06e4000
>  ? do_one_initcall+0x41/0x1f0
>  ? kmem_cache_alloc_trace+0x3f/0x1b0
>  ? do_init_module+0x5c/0x260
>  ? __do_sys_finit_module+0xa0/0xe0
>  ? do_syscall_64+0x35/0x80
>  ? entry_SYSCALL_64_after_hwframe+0x44/0xae
>  </TASK>
> kobject_add_internal failed for usb-003:004 with -EEXIST, don't try to register things with the same name in the same directory.
> libphy: mii_bus usb-003:004 failed to register
> asix: probe of 3-10.4:1.0 failed with error -22 
> usbcore: registered new interface driver asix
> 
> 
> Both these issues with "net: usb: asix: ax88772: add phylib support"
> (e532a096be0e) can be reproduced all the way from when it was introduced
> to linus current tree.
> 
> 
> I'm sorry to say that I don't know enough about either libphy or asix to
> figure out what cause the issues can be.
> 
> 
> 
> //Anton
> 

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