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* Thunderbolt, direct-complete and long suspend/resume time of Suspend-to-idle
@ 2020-03-11  5:39 Kai-Heng Feng
  2020-03-11 10:38 ` Mika Westerberg
  0 siblings, 1 reply; 8+ messages in thread
From: Kai-Heng Feng @ 2020-03-11  5:39 UTC (permalink / raw)
  To: Rafael Wysocki, Mika Westerberg
  Cc: Shih-Yuan Lee (FourDollars), Tiffany, Linux PCI, Linux PM, open list


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;

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...



^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2020-03-13 11:31 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-03-11  5:39 Thunderbolt, direct-complete and long suspend/resume time of Suspend-to-idle Kai-Heng Feng
2020-03-11 10:38 ` Mika Westerberg
2020-03-12  4:41   ` Kai-Heng Feng
2020-03-12  8:15     ` Mika Westerberg
2020-03-12 10:10       ` Kai-Heng Feng
2020-03-12 10:41         ` Mika Westerberg
2020-03-13  5:07           ` Kai-Heng Feng
2020-03-13 11:31             ` Mika Westerberg

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