I've been looking into this for the last few days and it turns out the issue is definitely caused by PCI link power management: Using the CONFIG_PCIEASPM_DEBUG config option of the kernel I was able to track the issue down to the PCI ASPM L1.2 power saving state (set link_state of the parent PCI bridge to 15 or 111 to enable everything except L1.2 [1]).
Not sure how to continue at this point, since PCIe ASPM is implemented in hardware and debugging would require special equipment, I really hope someone at Marvell steps up and has a look into this. It might also be possible that L1.2 is disabled on Windows, but I haven't found tools to read the L1 substates from the PCI configuration on Windows yet. Another interesting fact is that the random command timeouts I'm looking into here only seem to happen on some Surface devices using the 8897 chip via PCI, that is the Pro 4, Pro 2017, the Pro 6, Laptop 2 (see comments in [2]), but not on the Surface Book 2 (according to owners of the device). There are also multiple reports of the same issue on completely different devices to be found on the internet ([3], [4]), but those never got any attention by Marvell developers. [1] https://github.com/torvalds/linux/blob/master/drivers/pci/pcie/aspm.c#L28 [2] https://github.com/jakeday/linux-surface/issues/163 [3] https://www.spinics.net/lists/linux-wireless/msg159776.html [4] https://www.spinics.net/lists/linux-wireless/msg175943.html -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1730924 Title: Wifi does down "crash" in Surface Pro 4 Status in Linux: Confirmed Status in linux package in Ubuntu: Incomplete Bug description: I have a Surface Pro 4. The wifi works well in principle, but unfortunately it drops every x minutes. The only way to fix it I've found is to reboot the computer. lsb_release -rd Description: Ubuntu 17.10 Release: 17.10 ProblemType: Bug DistroRelease: Ubuntu 17.10 Package: linux-image-4.13.0-16-generic 4.13.0-16.19 ProcVersionSignature: Ubuntu 4.13.0-16.19-generic 4.13.4 Uname: Linux 4.13.0-16-generic x86_64 ApportVersion: 2.20.7-0ubuntu3.1 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: predatux 1537 F.... pulseaudio CurrentDesktop: KDE Date: Wed Nov 8 10:41:26 2017 HibernationDevice: RESUME=UUID=147af4ba-a4ce-41fe-a176-b36a1f6a590b Lsusb: Bus 002 Device 002: ID 045e:090c Microsoft Corp. Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 002: ID 045e:07e8 Microsoft Corp. Bus 001 Device 003: ID 1286:204c Marvell Semiconductor, Inc. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub MachineType: Microsoft Corporation Surface Pro 4 ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.13.0-16-generic root=UUID=125200b0-7377-4985-a217-15503781a525 ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-4.13.0-16-generic N/A linux-backports-modules-4.13.0-16-generic N/A linux-firmware 1.169 SourcePackage: linux UpgradeStatus: Upgraded to artful on 2017-10-22 (16 days ago) dmi.bios.date: 02/24/2017 dmi.bios.vendor: Microsoft Corporation dmi.bios.version: 106.1624.768 dmi.board.name: Surface Pro 4 dmi.board.vendor: Microsoft Corporation dmi.chassis.type: 9 dmi.chassis.vendor: Microsoft Corporation dmi.modalias: dmi:bvnMicrosoftCorporation:bvr106.1624.768:bd02/24/2017:svnMicrosoftCorporation:pnSurfacePro4:pvrD0B08F1C03P38:rvnMicrosoftCorporation:rnSurfacePro4:rvr:cvnMicrosoftCorporation:ct9:cvr: dmi.product.family: Surface dmi.product.name: Surface Pro 4 dmi.product.version: D:0B:08F:1C:03P:38 dmi.sys.vendor: Microsoft Corporation To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1730924/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
