+Cc workflows On 11/24/23 12:43, Greg Kroah-Hartman wrote: > On Thu, Nov 23, 2023 at 07:20:46PM +0100, Oleksandr Natalenko wrote: >> Hello. >> >> Since v6.6.2 kernel release I'm experiencing a regression with regard >> to USB ports behaviour after a suspend/resume cycle. >> >> If a USB port is empty before suspending, after resuming the machine >> the port doesn't work. After a device insertion there's no reaction in >> the kernel log whatsoever, although I do see that the device gets >> powered up physically. If the machine is suspended with a device >> inserted into the USB port, the port works fine after resume. >> >> This is an AMD-based machine with hci version 0x110 reported. As per >> the changelog between v6.6.1 and v6.6.2, 603 commits were backported >> into v6.6.2, and one of the commits was as follows: >> >> $ git log --oneline v6.6.1..v6.6.2 -- drivers/usb/host/xhci-pci.c >> 14a51fa544225 xhci: Loosen RPM as default policy to cover for AMD xHC >> 1.1 >> >> It seems that this commit explicitly enables runtime PM specifically >> for my platform. As per dmesg: >> >> v6.6.1: quirks 0x0000000000000410 v6.6.2: quirks 0x0000000200000410 >> >> Here, bit 33 gets set, which, as expected, corresponds to: >> >> drivers/usb/host/xhci.h 1895:#define XHCI_DEFAULT_PM_RUNTIME_ALLOW >> BIT_ULL(33) >> >> This commit is backported from the upstream commit 4baf12181509, which >> is one of 16 commits of the following series named "xhci features": >> >> https://lore.kernel.org/all/20231019102924.2797346-1-mathias.nyman@xxxxxxxxxxxxxxx/ >> >> It appears that there was another commit in this series, also from >> Basavaraj (in Cc), a5d6264b638e, which was not picked for v6.6.2, but >> which stated the following: >> >> Use the low-power states of the underlying platform to enable runtime >> PM. If the platform doesn't support runtime D3, then enabling default >> RPM will result in the controller malfunctioning, as in the case of >> hotplug devices not being detected because of a failed interrupt >> generation. >> >> It felt like this was exactly my case. So, I've conducted two tests: >> >> 1. Reverted 14a51fa544225 from v6.6.2. With this revert the USB ports >> started to work fine, just as they did in v6.6.1. 2. Left 14a51fa544225 >> in place, but also applied upstream a5d6264b638e on top of v6.6.2. With >> this patch added the USB ports also work after a suspend/resume cycle. >> >> This runtime PM enablement did also impact my AX200 Bluetooth device, >> resulting in long delays before headphones/speaker can connect, but >> I've solved this with btusb.enable_autosuspend=N. I think this has >> nothing to do with the original issue, and I'm OK with this workaround >> unless someone has got a different idea. >> >> With that, please consider either reverting 14a51fa544225 from the >> stable kernel, or applying a5d6264b638e in addition to it. Given the >> mainline kernel has got both of them, I'm in favour of applying >> additional commit to the stable kernel. > > I've applied this other commit as well to all of the affected branches, > thanks for letting us know. > >> I'm also Cc'ing all the people from our Mastodon discussion where I >> initially complained about the issue as well as about stable kernel >> branch stability: >> >> https://activitypub.natalenko.name/@oleksandr/statuses/01HFRXBYWMXF9G4KYPE3XHH0S8 >> >> I'm not going to expand more on that in this email, especially given >> Greg indicated he read the conversation, but I'm open to continuing >> this discussion as I still think that current workflow brings visible >> issues to ordinary users, and hence some adjustments should be made. > > What type of adjustments exactly? Testing on wide ranges of systems is > pretty hard, and this patch explicitly was set to be backported when it > hit Linus's tree, Are you sure about that "explicitly was set to be backported" part? According to Documentation/process/stable-kernel-rules.rst: > There are three options to submit a change to -stable trees: > > 1. Add a 'stable tag' to the description of a patch you then submit for > mainline inclusion. > 2. Ask the stable team to pick up a patch already mainlined. > 3. Submit a patch to the stable team that is equivalent to a change already > mainlined. I don't see a stable tag in 4baf12181509 ("xhci: Loosen RPM as default policy to cover for AMD xHC 1.1"), was it option 2 or 3 then? Do you mean the Fixes: tag? the docs only say that can replace the "# 3.3.x" part to determine where backporting should stop, but is not itself an explicit marking for stable backport? > it just looks like someone forgot to mark the > follow-up patch that you found also to be properly backported. > > We will always make mistakes, we are only human. The best thing to do > is if we get notified quickly of issues, like you did here, and work to > resolve them, as we have done here. So again, thanks for letting us > know about the problem, and be sure to let us know of any future issues > you might find as well. > > Remember, hardware is messy, and the kernel's job is to fix hardware > issues and quirks in it. Sometimes we get it wrong as we are trying to > fix up inconsistencies and they cause other problems, so in the end, we > can only grumble at the hardware companies for stuff like this, be > patient with those of us who have to deal with this mess :) > > thanks, > > greg k-h
