From: Kai-Heng Feng <kai.heng.feng@canonical.com>
To: Rafael Wysocki <rafael.j.wysocki@intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: "Shih-Yuan Lee (FourDollars)" <sylee@canonical.com>,
Tiffany <tiffany.wang@canonical.com>,
Linux PCI <linux-pci@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Thunderbolt, direct-complete and long suspend/resume time of Suspend-to-idle
Date: Wed, 11 Mar 2020 13:39:51 +0800 [thread overview]
Message-ID: <02700895-048F-4EA1-9E18-4883E83AE210@canonical.com> (raw)
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;
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...
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/pci.c#n4621
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/base/power/main.c#n1748
Kai-Heng
next reply other threads:[~2020-03-11 5:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-11 5:39 Kai-Heng Feng [this message]
2020-03-11 10:38 ` Thunderbolt, direct-complete and long suspend/resume time of Suspend-to-idle 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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