On 23.11.2020 15.54, Hans de Goede wrote: > Hi, > > On 11/11/20 3:31 PM, Mika Westerberg wrote: >> On Wed, Nov 11, 2020 at 12:27:32PM +0100, Hans de Goede wrote: >>> Hi, >>> >>> On 11/10/20 6:25 PM, Mika Westerberg wrote: >>>> On Tue, Nov 10, 2020 at 04:02:33PM +0000, Limonciello, Mario wrote: >>>>>> >>>>>> On Tue, Nov 10, 2020 at 11:57:07AM +0100, Bastien Nocera wrote: >>>>>>> Hey, >>>>>>> >>>>>>> systemd has been shipping this script to enable auto-suspend on a >>>>>>> number of USB and PCI devices: >>>>>>> >>>>>> https://github.com/systemd/systemd/blob/master/tools/chromiumos/gen_autosuspen >>>>>> d_rules.py >>>>>>> >>>>>>> The problem here is twofold. First, the list of devices is updated from >>>>>>> ChromeOS, and the original list obviously won't be updated by ChromeOS >>>>>>> developers unless a device listed exists in a ChromeBook computer, >>>>>>> which means a number of devices that do support autosuspend aren't >>>>>>> listed. >>>>>>> >>>>>>> The other problem is that this list needs to exist at all, and that it >>>>>>> doesn't seem possible for device driver developers (at various levels >>>>>>> of the stack) to opt-in to auto-suspend when all the variants of the >>>>>>> device (or at least detectable ones) support auto-suspend. >>>>>> >>>>>> A driver can say they support autosuspend today, but I think you are >>>>>> concerned about the devices that are controlled by class-compliant >>>>>> drivers, right? And for those, no, we can't do this in the kernel as >>>>>> there are just too many broken devices out there. >>>>>> >>>>> >>>>> I guess what Bastien is getting at is for newer devices supported by class >>>>> drivers rather than having to store an allowlist in udev rules, can we set >>>>> the allowlist in the kernel instead. Then distributions that either don't >>>>> use systemd or don't regularly update udev rules from systemd can take >>>>> advantage of better defaults on modern hardware. >>>>> >>>>> The one item that stood out to me in that rules file was 8086:a0ed. >>>>> It's listed as "Volteer XHCI", but that same device ID is actually present >>>>> in an XPS 9310 in front of me as well and used by the xhci-pci kernel module. >>>>> >>>>> Given we're effectively ending up with the combination of runtime PM turned >>>>> on by udev rules, do we need something like this for that ID: >>>>> >>>>> https://github.com/torvalds/linux/commit/6a7c533d4a1854f54901a065d8c672e890400d8a >>>>> >>>>> @Mika Westerberg should 8086:a0ed be quirked like the TCSS xHCI too? >>>> >>>> I think this one is the TGL PCH xHCI. The quirk currently for xHCI >>>> controllers that are part of the TCSS (Type-C SubSystem) where it is >>>> important to put all devices into low power mode whenever possible, >>>> otherwise it keeps the whole block on. >>> >>> Note that there are currently some IDs missing from the xHCIs which >>> are part of the TCSS too. At least the id for the xHCI in the thunderbolt >>> controller on the Lenovo T14 gen 1 is missing. I started a discussion >>> about extending the kernel quirk list for this vs switching to hwdb >>> a while a go: >>> >>> https://lore.kernel.org/linux-usb/b8b21ba3-0a8a-ff54-5e12-cf8960651086@xxxxxxxxxx/ >>> >>> The conclusion back then was to switch to hwdb, but I never got around to this. >> >> The reason I've added these to the xHCI driver is that it works even if >> you are running some really small userspace (like busybox). Also for the >> xHCI in TCSS we know for sure that it fully supports D3cold. >> >> (The one you refer above is actually mistake from my side as I never >> tested Alpine Ridge LP controller which I think this is). > > Ok, so I'll submit a patch adding the 15c1 product-id for the > INTEL_ALPINE_RIDGE_LP_2C_XHCI controller to the list of ids for which we > set the XHCI_DEFAULT_PM_RUNTIME_ALLOW quirk. To fix the much too high > idle-power consumption problem on devices with this Alpine Ridge variant. Thanks > >>>> Typically we haven't done that for PCH side xHCI controllers though, but >>>> I don't see why not if it works that is. Adding Mathias to comment more >>>> on that since he is the xHCI maintainer. >>> >>> If we are also going to enable this for the non TCSS Intel XHCI controllers, >>> maybe just uncondtionally enable it for all Intel XHCI controllers, or >>> if necessary do a deny-list for some older models and enable it for anything >>> not on the deny-list (so all newer models). That should avoid the game of >>> whack-a-mole which we will have with this otherwise. >> >> This is really up to Mathias to decide. I'm fine either way :) > > Ok, Matthias what do you think about this? I don't think we are ready to enable runtime pm as default for all Intel xHCI controllers. The risk of xHCI not waking up when user plugs a mouse/keyboard, making the system unusable just seems too high compared to the powersaving benefit. The powersaving benefit from autosuspending the TCSS xHCI is a lot better, and we, (Mika mostly) has been able to verify they work. So I propose we for now continue adding TCSS xHCI controllers to the allowlist in kernel. For others I think a userspace allow/denylist makes sense. Long term goal would be default allow for all, with short denylist in kernel. Thanks Mathias
