Message-ID: <f8f0eb8f7dd9fdcf0435fd67681ecbb359718e18.camel@collabora.com>
Subject: Re: [PATCH] net: usb: Correct PHY handling of smsc95xx
From:   Martyn Welch <martyn.welch@collabora.com>
To:     Ferry Toth <fntoth@gmail.com>, netdev@vger.kernel.org
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel@collabora.com,
        Steve Glendinning <steve.glendinning@shawell.net>,
        UNGLinuxDriver@microchip.com,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, stable@kernel.org
Date:   Mon, 29 Nov 2021 12:08:26 +0000
In-Reply-To: <5cd6fc87-0f8d-0b9b-42be-8180540a94e7@gmail.com>
References: <20211122184445.1159316-1-martyn.welch@collabora.com>
         <5cd6fc87-0f8d-0b9b-42be-8180540a94e7@gmail.com>
Organization: Collabora Ltd.
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On Sat, 2021-11-27 at 18:48 +0100, Ferry Toth wrote:
> Hi,
> 
> Op 22-11-2021 om 19:44 schreef Martyn Welch:
> > The smsc95xx driver is dropping phy speed settings and causing a
> > stack
> > trace at device unbind:
> > 
> > [  536.379147] smsc95xx 2-1:1.0 eth1: unregister 'smsc95xx' usb-
> > ci_hdrc.2-1, smsc95xx USB 2.0 Ethernet
> > [  536.425029] ------------[ cut here ]------------
> > [  536.429650] WARNING: CPU: 0 PID: 439 at fs/kernfs/dir.c:1535
> > kernfs_remove_by_name_ns+0xb8/0xc0
> > [  536.438416] kernfs: can not remove 'attached_dev', no directory
> > [  536.444363] Modules linked in: xts dm_crypt dm_mod atmel_mxt_ts
> > smsc95xx usbnet
> > [  536.451748] CPU: 0 PID: 439 Comm: sh Tainted: G        W        
> > 5.15.0 #1
> > [  536.458636] Hardware name: Freescale i.MX53 (Device Tree
> > Support)
> > [  536.464735] Backtrace:
> > [  536.467190] [<80b1c904>] (dump_backtrace) from [<80b1cb48>]
> > (show_stack+0x20/0x24)
> > [  536.474787]  r7:000005ff r6:8035b294 r5:600f0013 r4:80d8af78
> > [  536.480449] [<80b1cb28>] (show_stack) from [<80b1f764>]
> > (dump_stack_lvl+0x48/0x54)
> > [  536.488035] [<80b1f71c>] (dump_stack_lvl) from [<80b1f788>]
> > (dump_stack+0x18/0x1c)
> > [  536.495620]  r5:00000009 r4:80d9b820
> > [  536.499198] [<80b1f770>] (dump_stack) from [<80124fac>]
> > (__warn+0xfc/0x114)
> > [  536.506187] [<80124eb0>] (__warn) from [<80b1d21c>]
> > (warn_slowpath_fmt+0xa8/0xdc)
> > [  536.513688]  r7:000005ff r6:80d9b820 r5:80d9b8e0 r4:83744000
> > [  536.519349] [<80b1d178>] (warn_slowpath_fmt) from [<8035b294>]
> > (kernfs_remove_by_name_ns+0xb8/0xc0)
> > [  536.528416]  r9:00000001 r8:00000000 r7:824926dc r6:00000000
> > r5:80df6c2c r4:00000000
> > [  536.536162] [<8035b1dc>] (kernfs_remove_by_name_ns) from
> > [<80b1f56c>] (sysfs_remove_link+0x4c/0x50)
> > [  536.545225]  r6:7f00f02c r5:80df6c2c r4:83306400
> > [  536.549845] [<80b1f520>] (sysfs_remove_link) from [<806f9c8c>]
> > (phy_detach+0xfc/0x11c)
> > [  536.557780]  r5:82492000 r4:83306400
> > [  536.561359] [<806f9b90>] (phy_detach) from [<806f9cf8>]
> > (phy_disconnect+0x4c/0x58)
> > [  536.568943]  r7:824926dc r6:7f00f02c r5:82492580 r4:83306400
> > [  536.574604] [<806f9cac>] (phy_disconnect) from [<7f00a310>]
> > (smsc95xx_disconnect_phy+0x30/0x38 [smsc95xx])
> > [  536.584290]  r5:82492580 r4:82492580
> > [  536.587868] [<7f00a2e0>] (smsc95xx_disconnect_phy [smsc95xx])
> > from [<7f001570>] (usbnet_stop+0x70/0x1a0 [usbnet])
> > [  536.598161]  r5:82492580 r4:82492000
> > [  536.601740] [<7f001500>] (usbnet_stop [usbnet]) from
> > [<808baa70>] (__dev_close_many+0xb4/0x12c)
> > [  536.610466]  r8:83744000 r7:00000000 r6:83744000 r5:83745b74
> > r4:82492000
> > [  536.617170] [<808ba9bc>] (__dev_close_many) from [<808bab78>]
> > (dev_close_many+0x90/0x120)
> > [  536.625365]  r7:00000001 r6:83745b74 r5:83745b8c r4:82492000
> > [  536.631026] [<808baae8>] (dev_close_many) from [<808bf408>]
> > (unregister_netdevice_many+0x15c/0x704)
> > [  536.640094]  r9:00000001 r8:81130b98 r7:83745b74 r6:83745bc4
> > r5:83745b8c r4:82492000
> > [  536.647840] [<808bf2ac>] (unregister_netdevice_many) from
> > [<808bfa50>] (unregister_netdevice_queue+0xa0/0xe8)
> > [  536.657775]  r10:8112bcc0 r9:83306c00 r8:83306c80 r7:8291e420
> > r6:83744000 r5:00000000
> > [  536.665608]  r4:82492000
> > [  536.668143] [<808bf9b0>] (unregister_netdevice_queue) from
> > [<808bfac0>] (unregister_netdev+0x28/0x30)
> > [  536.677381]  r6:7f01003c r5:82492000 r4:82492000
> > [  536.682000] [<808bfa98>] (unregister_netdev) from [<7f000b40>]
> > (usbnet_disconnect+0x64/0xdc [usbnet])
> > [  536.691241]  r5:82492000 r4:82492580
> > [  536.694819] [<7f000adc>] (usbnet_disconnect [usbnet]) from
> > [<8076b958>] (usb_unbind_interface+0x80/0x248)
> > [  536.704406]  r5:7f01003c r4:83306c80
> > [  536.707984] [<8076b8d8>] (usb_unbind_interface) from
> > [<8061765c>] (device_release_driver_internal+0x1c4/0x1cc)
> > [  536.718005]  r10:8112bcc0 r9:80dff1dc r8:83306c80 r7:83744000
> > r6:7f01003c r5:00000000
> > [  536.725838]  r4:8291e420
> > [  536.728373] [<80617498>] (device_release_driver_internal) from
> > [<80617684>] (device_release_driver+0x20/0x24)
> > [  536.738302]  r7:83744000 r6:810d4f4c r5:8291e420 r4:8176ae30
> > [  536.743963] [<80617664>] (device_release_driver) from
> > [<806156cc>] (bus_remove_device+0xf0/0x148)
> > [  536.752858] [<806155dc>] (bus_remove_device) from [<80610018>]
> > (device_del+0x198/0x41c)
> > [  536.760880]  r7:83744000 r6:8116e2e4 r5:8291e464 r4:8291e420
> > [  536.766542] [<8060fe80>] (device_del) from [<80768fe8>]
> > (usb_disable_device+0xcc/0x1e0)
> > [  536.774576]  r10:8112bcc0 r9:80dff1dc r8:00000001 r7:8112bc48
> > r6:8291e400 r5:00000001
> > [  536.782410]  r4:83306c00
> > [  536.784945] [<80768f1c>] (usb_disable_device) from [<80769c30>]
> > (usb_set_configuration+0x514/0x8dc)
> > [  536.794011]  r10:00000000 r9:00000000 r8:832c3600 r7:00000004
> > r6:810d5688 r5:00000000
> > [  536.801844]  r4:83306c00
> > [  536.804379] [<8076971c>] (usb_set_configuration) from
> > [<80775fac>] (usb_generic_driver_disconnect+0x34/0x38)
> > [  536.814236]  r10:832c3610 r9:83745ef8 r8:832c3600 r7:00000004
> > r6:810d5688 r5:83306c00
> > [  536.822069]  r4:83306c00
> > [  536.824605] [<80775f78>] (usb_generic_driver_disconnect) from
> > [<8076b850>] (usb_unbind_device+0x30/0x70)
> > [  536.834100]  r5:83306c00 r4:810d5688
> > [  536.837678] [<8076b820>] (usb_unbind_device) from [<8061765c>]
> > (device_release_driver_internal+0x1c4/0x1cc)
> > [  536.847432]  r5:822fb480 r4:83306c80
> > [  536.851009] [<80617498>] (device_release_driver_internal) from
> > [<806176a8>] (device_driver_detach+0x20/0x24)
> > [  536.860853]  r7:00000004 r6:810d4f4c r5:810d5688 r4:83306c80
> > [  536.866515] [<80617688>] (device_driver_detach) from
> > [<80614d98>] (unbind_store+0x70/0xe4)
> > [  536.874793] [<80614d28>] (unbind_store) from [<80614118>]
> > (drv_attr_store+0x30/0x3c)
> > [  536.882554]  r7:00000000 r6:00000000 r5:83739200 r4:80614d28
> > [  536.888217] [<806140e8>] (drv_attr_store) from [<8035cb68>]
> > (sysfs_kf_write+0x48/0x54)
> > [  536.896154]  r5:83739200 r4:806140e8
> > [  536.899732] [<8035cb20>] (sysfs_kf_write) from [<8035be84>]
> > (kernfs_fop_write_iter+0x11c/0x1d4)
> > [  536.908446]  r5:83739200 r4:00000004
> > [  536.912024] [<8035bd68>] (kernfs_fop_write_iter) from
> > [<802b87fc>] (vfs_write+0x258/0x3e4)
> > [  536.920317]  r10:00000000 r9:83745f58 r8:83744000 r7:00000000
> > r6:00000004 r5:00000000
> > [  536.928151]  r4:82adacc0
> > [  536.930687] [<802b85a4>] (vfs_write) from [<802b8b0c>]
> > (ksys_write+0x74/0xf4)
> > [  536.937842]  r10:00000004 r9:007767a0 r8:83744000 r7:00000000
> > r6:00000000 r5:82adacc0
> > [  536.945676]  r4:82adacc0
> > [  536.948213] [<802b8a98>] (ksys_write) from [<802b8ba4>]
> > (sys_write+0x18/0x1c)
> > [  536.955367]  r10:00000004 r9:83744000 r8:80100244 r7:00000004
> > r6:76f47b58 r5:76fc0350
> > [  536.963200]  r4:00000004
> > [  536.965735] [<802b8b8c>] (sys_write) from [<80100060>]
> > (ret_fast_syscall+0x0/0x48)
> > [  536.973320] Exception stack(0x83745fa8 to 0x83745ff0)
> > [  536.978383] 5fa0:                   00000004 76fc0350 00000001
> > 007767a0 00000004 00000000
> > [  536.986569] 5fc0: 00000004 76fc0350 76f47b58 00000004 76f47c7c
> > 76f48114 00000000 7e87991c
> > [  536.994753] 5fe0: 00000498 7e879908 76e6dce8 76eca2e8
> > [  536.999922] ---[ end trace 9b835d809816b435 ]---
> 
> I am testing this patch on Intel Edison-Arduino with Linux 5.15.1.
> I had reported this issue earlier as
> https://lore.kernel.org/linux-usb/07628a9b-1370-98b7-c1f3-98b9bf8cc38f@gmail.com/
> 
> This patch indeed resolves the above crash on each unplug.
> 
> > The driver should not be connecting and disconnecting the PHY when
> > the
> > device is opened and closed, it should be stopping and starting the
> > PHY. The
> > phy should be connected as part of binding and disconnected during
> > unbinding.
> > 
> > As this results in the PHY not being reset during open, link speed,
> > etc.
> > settings set prior to the link coming up are now not being lost.
> > 
> > It is necessary for phy_stop() to only be called when the phydev
> > still
> > exists (resolving the above stack trace). When unbinding, ".unbind"
> > will be
> > called prior to ".stop", with phy_disconnect() already having
> > called
> > phy_stop() before the phydev becomes inaccessible.
> 
> 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...


> 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

> 
> > Signed-off-by: Martyn Welch <martyn.welch@collabora.com>
> > Cc: Steve Glendinning <steve.glendinning@shawell.net>
> > Cc: UNGLinuxDriver@microchip.com
> > Cc: "David S. Miller" <davem@davemloft.net>
> > Cc: Jakub Kicinski <kuba@kernel.org>
> > Cc: stable@kernel.org # v5.15
> > ---
> >   drivers/net/usb/smsc95xx.c | 55 ++++++++++++++++++---------------
> > -----
> >   1 file changed, 26 insertions(+), 29 deletions(-)
> > 
> > diff --git a/drivers/net/usb/smsc95xx.c
> > b/drivers/net/usb/smsc95xx.c
> > index 26b1bd8e845b..f91dabd65ecd 100644
> > --- a/drivers/net/usb/smsc95xx.c
> > +++ b/drivers/net/usb/smsc95xx.c
> > @@ -1049,6 +1049,14 @@ static const struct net_device_ops
> > smsc95xx_netdev_ops = {
> >         .ndo_set_features       = smsc95xx_set_features,
> >   };
> >   
> > +static void smsc95xx_handle_link_change(struct net_device *net)
> > +{
> > +       struct usbnet *dev = netdev_priv(net);
> > +
> > +       phy_print_status(net->phydev);
> > +       usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
> > +}
> > +
> >   static int smsc95xx_bind(struct usbnet *dev, struct usb_interface
> > *intf)
> >   {
> >         struct smsc95xx_priv *pdata;
> > @@ -1153,6 +1161,17 @@ static int smsc95xx_bind(struct usbnet *dev,
> > struct usb_interface *intf)
> >         dev->net->min_mtu = ETH_MIN_MTU;
> >         dev->net->max_mtu = ETH_DATA_LEN;
> >         dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;
> > +
> > +       ret = phy_connect_direct(dev->net, pdata->phydev,
> > +                                &smsc95xx_handle_link_change,
> > +                                PHY_INTERFACE_MODE_MII);
> > +       if (ret) {
> > +               netdev_err(dev->net, "can't attach PHY to %s\n",
> > pdata->mdiobus->id);
> > +               goto unregister_mdio;
> > +       }
> > +
> > +       phy_attached_info(dev->net->phydev);
> > +
> >         return 0;
> >   
> >   unregister_mdio:
> > @@ -1170,47 +1189,25 @@ static void smsc95xx_unbind(struct usbnet
> > *dev, struct usb_interface *intf)
> >   {
> >         struct smsc95xx_priv *pdata = dev->driver_priv;
> >   
> > +       phy_disconnect(dev->net->phydev);
> >         mdiobus_unregister(pdata->mdiobus);
> >         mdiobus_free(pdata->mdiobus);
> >         netif_dbg(dev, ifdown, dev->net, "free pdata\n");
> >         kfree(pdata);
> >   }
> >   
> > -static void smsc95xx_handle_link_change(struct net_device *net)
> > -{
> > -       struct usbnet *dev = netdev_priv(net);
> > -
> > -       phy_print_status(net->phydev);
> > -       usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
> > -}
> > -
> >   static int smsc95xx_start_phy(struct usbnet *dev)
> >   {
> > -       struct smsc95xx_priv *pdata = dev->driver_priv;
> > -       struct net_device *net = dev->net;
> > -       int ret;
> > +       phy_start(dev->net->phydev);
> >   
> > -       ret = smsc95xx_reset(dev);
> > -       if (ret < 0)
> > -               return ret;
> > -
> > -       ret = phy_connect_direct(net, pdata->phydev,
> > -                                &smsc95xx_handle_link_change,
> > -                                PHY_INTERFACE_MODE_MII);
> > -       if (ret) {
> > -               netdev_err(net, "can't attach PHY to %s\n", pdata-
> > >mdiobus->id);
> > -               return ret;
> > -       }
> > -
> > -       phy_attached_info(net->phydev);
> > -       phy_start(net->phydev);
> >         return 0;
> >   }
> >   
> > -static int smsc95xx_disconnect_phy(struct usbnet *dev)
> > +static int smsc95xx_stop(struct usbnet *dev)
> >   {
> > -       phy_stop(dev->net->phydev);
> > -       phy_disconnect(dev->net->phydev);
> > +       if (dev->net->phydev)
> > +               phy_stop(dev->net->phydev);
> > +
> >         return 0;
> >   }
> >   
> > @@ -1965,7 +1962,7 @@ static const struct driver_info smsc95xx_info
> > = {
> >         .unbind         = smsc95xx_unbind,
> >         .link_reset     = smsc95xx_link_reset,
> >         .reset          = smsc95xx_start_phy,
> > -       .stop           = smsc95xx_disconnect_phy,
> > +       .stop           = smsc95xx_stop,
> >         .rx_fixup       = smsc95xx_rx_fixup,
> >         .tx_fixup       = smsc95xx_tx_fixup,
> >         .status         = smsc95xx_status,
> > 
>