> On Mar 11, 2020, at 18:38, Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > > On Wed, Mar 11, 2020 at 01:39:51PM +0800, Kai-Heng Feng wrote: >> Hi, >> >> I am currently investigating long suspend and resume time of suspend-to-idle. >> It's because Thunderbolt bridges need to wait for 1100ms [1] for runtime-resume on system suspend, and also for system resume. >> >> I made a quick hack to the USB driver and xHCI driver to support direct-complete, but I failed to do so for the parent PCIe bridge as it always disables the direct-complete [2], since device_may_wakeup() returns true for the device: >> >> /* Avoid direct_complete to let wakeup_path propagate. */ >> if (device_may_wakeup(dev) || dev->power.wakeup_path) >> dev->power.direct_complete = false; > > You need to be careful here because otherwise you end up situation where > the link is not properly trained and we tear down the whole tree of > devices which is worse than waiting bit more for resume. My idea is to direct-complete when there's no PCI or USB device plugged into the TBT, and use pm_reuqest_resume() in complete() so it won't block resume() or resume_noirq(). > >> Once the direct-complete is disabled, system suspend/resume is used hence the delay in [1] is making the resume really slow. >> So how do we make suspend-to-idle faster? I have some ideas but I am not sure if they are feasible: >> - Make PM core know the runtime_suspend() already use the same wakeup as suspend(), so it doesn't need to use device_may_wakeup() check to determine direct-complete. >> - Remove the DPM_FLAG_NEVER_SKIP flag in pcieport driver, and use pm_request_resume() in its complete() callback to prevent blocking the resume process. >> - Reduce the 1100ms delay. Maybe someone knows the values used in macOS and Windows... > > Which system this is? ICL? CML-H + Titan Ridge. > I think it is the TBT root ports only that do > not support active link reporting. The PCIe spec is not entirely clear > about root ports since it explictly mentions only downstream ports so > one option would be to check for root port and that it supports gen 3 > speeds and based on that wait for max say 2 * 100ms or something like > that. So 200ms for rootport, but still 1100ms for downstream ports? Kai-Heng
