From: Kai-Heng Feng <firstname.lastname@example.org>
To: Mika Westerberg <email@example.com>
Cc: Rafael Wysocki <firstname.lastname@example.org>,
"Shih-Yuan Lee (FourDollars)" <email@example.com>,
Linux PCI <firstname.lastname@example.org>,
Linux PM <email@example.com>,
open list <firstname.lastname@example.org>
Subject: Re: Thunderbolt, direct-complete and long suspend/resume time of Suspend-to-idle
Date: Thu, 12 Mar 2020 12:41:08 +0800 [thread overview]
Message-ID: <E3DA71C8-96A7-482E-B41F-8145979F88F4@canonical.com> (raw)
> On Mar 11, 2020, at 18:38, Mika Westerberg <email@example.com> wrote:
> On Wed, Mar 11, 2020 at 01:39:51PM +0800, Kai-Heng Feng wrote:
>> I am currently investigating long suspend and resume time of suspend-to-idle.
>> It's because Thunderbolt bridges need to wait for 1100ms  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 , 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  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
So 200ms for rootport, but still 1100ms for downstream ports?
next prev parent reply other threads:[~2020-03-12 4:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
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
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).