From: Alan Stern <stern@rowland.harvard.edu>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux PM list <linux-pm@vger.kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
Aaron Lu <aaron.lu@intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Kevin Hilman <khilman@linaro.org>,
Ulf Hansson <ulf.hansson@linaro.org>
Subject: Re: [RFC][PATCH 2/3] PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily
Date: Thu, 15 May 2014 10:29:42 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1405151024060.1415-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <20140515060924.69ae7486@ultegra>
On Thu, 15 May 2014, Jacob Pan wrote:
> > > should we respect ignore_children flag here? not all parent devices
> > > create children with proper .prepare() function. this allows parents
> > > override children.
> > > I am looking at USB, a USB device could have logical children such
> > > as ep_xx, they don't go through the same subsystem .prepare().
> >
> > Well, I'm not sure about that. Let me consider that for a while.
> OK. let me be more clear about the situation i see in USB. Correct me
> if I am wrong, a USB device will always has at least one endpoint/ep_00
> as a kid for control pipe, it is a logical device. So when
> device_prepare() is called, its call back is NULL which
> makes .direct_complete = 0. Since children device suspend is called
> before parents, the parents .direct_complete flag will always get
> cleared.
>
> What i am trying to achieve here is to see if we avoid resuming
> built-in (hardwired connect_type) non-hub USB devices based on this new
> patchset. E.g. we don't want to resume/suspend USB camera every time in
> system suspend/resume cycle if they are already rpm suspended. We can
> save ~100ms resume time for the devices we have tested.
This is a good point, but I don't think it is at all related to
ignore_children.
Instead, it seems that the best way to solve it would be to add a
->prepare() handler for usb_ep_device_type that would always turn
on direct_complete.
Alan Stern
next prev parent reply other threads:[~2014-05-15 14:29 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-13 1:02 [RFC][PATCH 0/3] PM / sleep: Avoid resuming runtime-suspended devices during system suspend Rafael J. Wysocki
2014-05-13 1:03 ` [RFC][PATCH 1/3] PM / sleep: Move runtime PM barrier invocation to device_prepare() Rafael J. Wysocki
2014-05-13 9:16 ` Ulf Hansson
2014-05-13 10:35 ` Rafael J. Wysocki
2014-05-13 10:59 ` Ulf Hansson
2014-05-13 15:07 ` Rafael J. Wysocki
2014-05-13 15:19 ` Rafael J. Wysocki
2014-05-13 1:10 ` [RFC][PATCH 2/3] PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily Rafael J. Wysocki
2014-05-13 9:30 ` Ulf Hansson
2014-05-13 14:49 ` Alan Stern
2014-05-13 15:13 ` Rafael J. Wysocki
2014-05-13 15:12 ` Alan Stern
2014-05-13 15:43 ` Rafael J. Wysocki
2014-05-13 15:46 ` Alan Stern
2014-05-13 16:16 ` Rafael J. Wysocki
2014-05-13 16:19 ` Alan Stern
2014-05-13 21:29 ` Rafael J. Wysocki
2014-05-14 14:53 ` Alan Stern
2014-05-15 11:13 ` Rafael J. Wysocki
2014-05-16 0:45 ` [PATCH 0/3] (was: Re: PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily) Rafael J. Wysocki
2014-05-16 0:46 ` [PATCH 1/3] PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily Rafael J. Wysocki
2014-05-16 14:27 ` Alan Stern
2014-05-16 21:10 ` Rafael J. Wysocki
2014-05-16 0:47 ` [PATCH 2/3] PM / sleep: Update device PM documentation to cover direct_complete Rafael J. Wysocki
2014-05-16 0:48 ` [PATCH 3/3][Resend] ACPI / PM: Avoid resuming devices in ACPI PM domain during system suspend Rafael J. Wysocki
2014-05-16 22:18 ` [PATCH 3/3][update] " Rafael J. Wysocki
2014-05-15 12:06 ` [RFC][PATCH 2/3] PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily Ulf Hansson
2014-05-15 12:55 ` Rafael J. Wysocki
2014-05-15 17:35 ` Kevin Hilman
2014-05-14 22:24 ` Jacob Pan
2014-05-15 11:11 ` Rafael J. Wysocki
2014-05-15 13:09 ` Jacob Pan
2014-05-15 14:29 ` Alan Stern [this message]
2014-05-15 7:03 ` Jacob Pan
2014-05-15 15:58 ` Alan Stern
2014-05-16 15:20 ` Jacob Pan
2014-05-16 21:08 ` Rafael J. Wysocki
2014-05-19 9:18 ` Jacob Pan
2014-05-19 19:53 ` Alan Stern
2014-05-19 20:13 ` Rafael J. Wysocki
2014-05-19 20:20 ` Rafael J. Wysocki
2014-05-13 1:10 ` [RFC][PATCH 3/3] ACPI / PM: Avoid resuming devices in ACPI PM domain during system suspend Rafael J. Wysocki
2014-05-13 14:45 ` [RFC][PATCH 0/3] PM / sleep: Avoid resuming runtime-suspended devices " Alan Stern
2014-05-13 15:25 ` Rafael J. Wysocki
2014-05-13 15:25 ` Alan Stern
2014-05-13 15:46 ` Rafael J. Wysocki
Reply instructions:
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:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Pine.LNX.4.44L0.1405151024060.1415-100000@iolanthe.rowland.org \
--to=stern@rowland.harvard.edu \
--cc=aaron.lu@intel.com \
--cc=jacob.jun.pan@linux.intel.com \
--cc=khilman@linaro.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=mika.westerberg@linux.intel.com \
--cc=rjw@rjwysocki.net \
--cc=ulf.hansson@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* 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).