Re: [PATCH] net: usb: Correct PHY handling of smsc95xx

[Ferry Toth <fntoth@gmail.com>]

Op 30-11-2021 om 19:52 schreef Martyn Welch:
> On Mon, 2021-11-29 at 15:16 +0100, Ferry Toth wrote:
>> Hi,
>> Op 29-11-2021 om 13:08 schreef Martyn Welch:
>>   
>>> On Sat, 2021-11-27 at 18:48 +0100, Ferry Toth wrote:
>>>   
>>>>
>>>> The patch introduces a new error on each unplug:
>>>>
>>>> usb 1-1: USB disconnect, device number 2
>>>> usb 1-1.1: USB disconnect, device number 3
>>>> smsc95xx 1-1.1:1.0 eth0: unregister 'smsc95xx' usb-xhci-hcd.1.auto-
>>>> 1.1,
>>>> smsc95xx USB 2.0 Ethernet
>>>> smsc95xx 1-1.1:1.0 eth0: Link is Down
>>>> smsc95xx 1-1.1:1.0 eth0: Failed to read reg index 0x00000114: -19
>>>> smsc95xx 1-1.1:1.0 eth0: Error reading MII_ACCESS
>>>> smsc95xx 1-1.1:1.0 eth0: __smsc95xx_mdio_read: MII is busy
>>>> smsc95xx 1-1.1:1.0 eth0: Failed to read reg index 0x00000114: -19
>>>> smsc95xx 1-1.1:1.0 eth0: Error reading MII_ACCESS
>>>> smsc95xx 1-1.1:1.0 eth0: __smsc95xx_mdio_read: MII is busy
>>>> smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup
>>>>
>>> Agh! Somehow missed that. I'm looking into it...
>>   That would be great!
>>   
> 
> They appear as a result of phy_disconnect() being called in unbind()
> when the hardware has already been disconnected (which is kinda likely
> to physically be the case with USB devices...). The PHY is not going to
> be accessible, but such calls *are* needed for instances where we are
> unbinding without the device having been physically removed and want to
> put the device in a suitable state. Failing with -ENODEV (as it
> currently does) seems to be the right thing to do.
> 
> I wonder whether removing some of these error messages might be an
> option? It appears that some of them are present in other drivers, but
> I don't know whether such messages get displayed when that hardware is
> unplugged too or whether I'm missing something that protects against
> that.
I just retried 5.10.63 and found it did not yet have the crash that you 
fix here. But it did have the above Error reading MII_ACCESS. So 
apparently this is more of an older annoyance since smsc95xx v2.00?
>>>
>>>   
>>>> Also as reported earlier, (only) on first plug the more worrying
>>>> but
>>>> possibly unrelated crash still happens:
>>>> ------------[ cut here ]------------
>>>> DMA-API: xhci-hcd xhci-hcd.1.auto: cacheline tracking EEXIST,
>>>> overlapping mappings aren't supported
>>>> WARNING: CPU: 0 PID: 23 at kernel/dma/debug.c:570
>>>> add_dma_entry+0x1d9/0x270
>>>> Modules linked in: rfcomm iptable_nat bnep usb_f_uac2 u_audio
>>>> snd_sof_nocodec usb_f_mass_storage usb_f_eem u_ether
>>>> spi_pxa2xx_platform
>>>> dw_dmac usb_f_serial u_serial libcomposite intel_mrfld_pwrbtn
>>>> snd_sof_pci_intel_tng pwm_lpss_pci intel_mrfld_adc pwm_lpss
>>>> snd_sof_pci
>>>> snd_sof_intel_ipc snd_sof_intel_atom dw_dmac_pci dw_dmac_core
>>>> snd_sof
>>>> snd_sof_xtensa_dsp snd_soc_acpi spi_pxa2xx_pci brcmfmac brcmutil
>>>> hci_uart leds_gpio btbcm ti_ads7950 industrialio_triggered_buffer
>>>> kfifo_buf tun ledtrig_timer ledtrig_heartbeat mmc_block
>>>> extcon_intel_mrfld sdhci_pci cqhci sdhci led_class mmc_core
>>>> intel_soc_pmic_mrfld btrfs libcrc32c xor zstd_compress zlib_deflate
>>>> raid6_pq
>>>> CPU: 0 PID: 23 Comm: kworker/0:1 Not tainted 5.15.1-edison-acpi-
>>>> standard #1
>>>> Hardware name: Intel Corporation Merrifield/BODEGA BAY, BIOS 542
>>>> 2015.01.21:18.19.48
>>>> Workqueue: usb_hub_wq hub_event
>>>> RIP: 0010:add_dma_entry+0x1d9/0x270
>>>> Code: ff 0f 84 97 00 00 00 4c 8b 67 50 4d 85 e4 75 03 4c 8b 27 e8
>>>> 39
>>>> ff
>>>> 52 00 48 89 c6 4c 89 e2 48 c7 c7 f0 ab e7 a7 e8 c7 5c b5 00 <0f> 0b
>>>> 48
>>>> 85 ed 0f 85 a4 b3 b5 00 8b 05 46 38 9f 01 85 c0 0f 85 df
>>>> RSP: 0000:ffffb047400cfac8 EFLAGS: 00010282
>>>> RAX: 0000000000000000 RBX: 00000000ffffffff RCX: ffff9e25fe217478
>>>> RDX: 00000000ffffffd8 RSI: 0000000000000027 RDI: ffff9e25fe217470
>>>> RBP: ffff9e25c12ff780 R08: ffffffffa83359a8 R09: 0000000000009ffb
>>>> R10: 00000000ffffe000 R11: 3fffffffffffffff R12: ffff9e25c8a24040
>>>> R13: 0000000000000001 R14: 0000000000000206 R15: 00000000000f8be4
>>>> FS:  0000000000000000(0000) GS:ffff9e25fe200000(0000)
>>>> knlGS:0000000000000000
>>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>> CR2: 00007f62c6d586d8 CR3: 0000000002f3c000 CR4: 00000000001006f0
>>>> Call Trace:
>>>>    dma_map_page_attrs+0xfb/0x250
>>>>    ? usb_hcd_link_urb_to_ep+0x14/0xa0
>>>>    usb_hcd_map_urb_for_dma+0x3b1/0x4e0
>>>>    usb_hcd_submit_urb+0x93/0xbb0
>>>>    ? create_prof_cpu_mask+0x20/0x20
>>>>    ? arch_stack_walk+0x73/0xf0
>>>>    ? usb_hcd_link_urb_to_ep+0x14/0xa0
>>>>    ? prepare_transfer+0xff/0x140
>>>>    usb_start_wait_urb+0x60/0x160
>>>>    usb_control_msg+0xda/0x140
>>>>    hub_ext_port_status+0x82/0x100
>>>>    hub_event+0x1b1/0x1830
>>>>    ? hub_activate+0x58c/0x860
>>>>    process_one_work+0x1d4/0x370
>>>>    worker_thread+0x48/0x3d0
>>>>    ? rescuer_thread+0x360/0x360
>>>>    kthread+0x122/0x140
>>>>    ? set_kthread_struct+0x40/0x40
>>>>    ret_from_fork+0x22/0x30
>>>> ---[ end trace da6ffcd9fad23a74 ]---
>>>> DMA-API: Mapped at:
>>>>    debug_dma_map_page+0x60/0xf0
>>>>    dma_map_page_attrs+0xfb/0x250
>>>>    usb_hcd_map_urb_for_dma+0x3b1/0x4e0
>>>>    usb_hcd_submit_urb+0x93/0xbb0
>>>>    usb_start_wait_urb+0x60/0x160
>>>> usb 1-1.1: new high-speed USB device number 3 using xhci-hcd
>>>> usb 1-1.1: New USB device found, idVendor=0424, idProduct=ec00,
>>>> bcdDevice= 2.00
>>>> usb 1-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
>>>> usb 1-1.1: Product: LAN9514
>>>> usb 1-1.1: Manufacturer: SMSC
>>>> usb 1-1.1: SerialNumber: 00951d0d
>>>>
>>>>
>>> I'm not seeing that at all, but I've also been developing and testing
>>> on an ARM based device that has the LAN9500A I'm using built into it.
>>>
>>> I have also recently got a LAN9500A devkit which I've tried on my
>>> Ryzen
>>> laptop and that's not throwing that error either.
>>>
>>> Martyn
>> Yes I am using the LAN9514 Evaluation board (EVB9514). Plugging the
>> board into my desktop with 5.15 Ubuntu PPA kernel I also don't see this
>> crash.
>> OTOH I'm building vanilla kernel so no idea why this happens. It might
>> be that I have CONFIG_DMA_API_DEBUG and Ubuntu not.
>>   
> 
> I suspect this is probably unrelated (directly) to the driver then.

Maybe not related to this driver but possibly an old bug in hub.c which 
only surfaces now due to patch "[PATCH] dma debug: report -EEXIST errors 
in add_dma_entry"? And only shows when CONFIG_DMA_API_DEBUG is set?

Ferry

> Martyn
> 
>>