On Fri, Nov 24, 2023 at 01:59:24PM +0100, Vlastimil Babka wrote: > +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? No, I mean the "The subsystem maintainer knew this needed to be added to the stable trees so they told the stable maintainer to do so." Now the fact that I am both people at once, and did so in my own head instead of writing myself a public email, might not have made this all that obvious :) thanks, gre gk-h
