linux-kernel - Re: [PATCH] PCI: qcom: Implement shutdown() callback

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Message-ID: <Z-4-A29UddizBUPz@ryzen>
Date: Thu, 3 Apr 2025 09:51:31 +0200
From: Niklas Cassel <cassel@...nel.org>
To: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org, quic_mrana@...cinc.com,
	quic_vbadigan@...cinc.com, quic_ramkri@...cinc.com,
	quic_vpernami@...cinc.com
Subject: Re: [PATCH] PCI: qcom: Implement shutdown() callback

Hello Krishna,

On Thu, Apr 03, 2025 at 09:26:08AM +0530, Krishna Chaitanya Chundru wrote:
> On 4/2/2025 6:14 PM, Niklas Cassel wrote:
> > 
> > Out of curiosity, I tried something similar to on pcie-dw-rockchip.c
> > 
> > Simply having a ->shutdown() callback that only calls dw_pcie_host_deinit()
> > was enough for me to produce:
> > 
> > [   40.209887] r8169 0004:41:00.0 eth0: Link is Down
> > [   40.216572] ------------[ cut here ]------------
> > [   40.216986] called from state HALTED
> > [   40.217317] WARNING: CPU: 7 PID: 265 at drivers/net/phy/phy.c:1630 phy_stop+0x134/0x1a0
> > [   40.218024] Modules linked in: rk805_pwrkey hantro_vpu v4l2_jpeg v4l2_vp9 v4l2_h264 v4l2_mem2mem videobuf2_v4l2 videobuf2_dma_contig videobuf2_memops videobuf2_common vidf
> > [   40.220267] CPU: 7 UID: 0 PID: 265 Comm: init Not tainted 6.14.0+ #134 PREEMPT
> > [   40.220908] Hardware name: Radxa ROCK 5B (DT)
> > [   40.221289] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > [   40.221899] pc : phy_stop+0x134/0x1a0
> > [   40.222222] lr : phy_stop+0x134/0x1a0
> > [   40.222546] sp : ffff800082213820
> > [   40.222836] x29: ffff800082213820 x28: ffff45ec84b30000 x27: 0000000000000000
> > [   40.223463] x26: 0000000000000000 x25: 0000000000000000 x24: ffffbe8df7fde030
> > [   40.224088] x23: ffff800082213990 x22: 0000000000000001 x21: ffff45ec80e10000
> > [   40.224714] x20: ffff45ec82cb40c8 x19: ffff45ec82ccc000 x18: 0000000000000006
> > [   40.225340] x17: 000000040044ffff x16: 005000f2b5503510 x15: 0720072007200720
> > [   40.225966] x14: 0720072007200720 x13: 0720072007200720 x12: 0720072007200720
> > [   40.226592] x11: 0000000000000058 x10: 0000000000000018 x9 : ffffbe8df556469c
> > [   40.227217] x8 : 0000000000000268 x7 : ffffbe8df7a48648 x6 : ffffbe8df7a48648
> > [   40.227842] x5 : 0000000000017fe8 x4 : 0000000000000000 x3 : 0000000000000000
> > [   40.228468] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff45ec84b30000
> > [   40.229093] Call trace:
> > [   40.229308]  phy_stop+0x134/0x1a0 (P)
> > [   40.229634]  rtl8169_down+0x34/0x280
> > [   40.229952]  rtl8169_close+0x64/0x100
> > [   40.230275]  __dev_close_many+0xbc/0x1f0
> > [   40.230621]  dev_close_many+0x94/0x160
> > [   40.230951]  unregister_netdevice_many_notify+0x14c/0x9c0
> > [   40.231426]  unregister_netdevice_queue+0xe4/0x100
> > [   40.231848]  unregister_netdev+0x2c/0x60
> > [   40.232193]  rtl_remove_one+0xa0/0xe0
> > [   40.232517]  pci_device_remove+0x4c/0xf8
> > [   40.232864]  device_remove+0x54/0x90
> > [   40.233182]  device_release_driver_internal+0x1d4/0x238
> > [   40.233643]  device_release_driver+0x20/0x38
> > [   40.234019]  pci_stop_bus_device+0x84/0xe0
> > [   40.234381]  pci_stop_bus_device+0x40/0xe0
> > [   40.234741]  pci_stop_root_bus+0x48/0x80
> > [   40.235087]  dw_pcie_host_deinit+0x34/0xe0
> > [   40.235452]  rockchip_pcie_shutdown+0x24/0x48
> > [   40.235839]  platform_shutdown+0x2c/0x48
> > [   40.236187]  device_shutdown+0x150/0x278
> > [   40.236533]  kernel_restart+0x4c/0xb8
> > [   40.236859]  __do_sys_reboot+0x178/0x280
> > [   40.237206]  __arm64_sys_reboot+0x2c/0x40
> > [   40.237561]  invoke_syscall+0x50/0x120
> > [   40.237891]  el0_svc_common.constprop.0+0x48/0xf0
> > [   40.238305]  do_el0_svc+0x24/0x38
> > [   40.238597]  el0_svc+0x30/0xd0
> > [   40.238868]  el0t_64_sync_handler+0x10c/0x138
> > [   40.239251]  el0t_64_sync+0x198/0x1a0
> > [   40.239575] ---[ end trace 0000000000000000 ]---
> > 
> Hi Niklas,
> 
> The issue which you are seeing with specific to the RealTek ethernet
> driver and should be fixed by RealTek driver nothing to do with the host
> controller.

The warning comes from:
drivers/net/phy/phy.c:phy_stop()
so from the networking phylib.

Doing a simple:
$ git grep -p phy_stop

shows that practially all Ethernet drivers call phy_stop() from the
.ndo_stop() callback.

So after your suggested patch, you should see this warning appear with
any NIC, if connected to your PCIe controller.

You might not care, which is fine, I simply wanted to inform you about it,
since it is not only realtek, it is any NIC.


Kind regards,
Niklas