From: Kevin Hilman <khilman@linaro.org>
To: Alan Stern <stern@rowland.harvard.edu>
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>,
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 10:35:51 -0700 [thread overview]
Message-ID: <7hiop7ymfc.fsf@paris.lan> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1405131139510.1098-100000@iolanthe.rowland.org> (Alan Stern's message of "Tue, 13 May 2014 11:46:55 -0400 (EDT)")
Alan Stern <stern@rowland.harvard.edu> writes:
> On Tue, 13 May 2014, Rafael J. Wysocki wrote:
>
>> > A wakeup request from the hardware could cause a runtime resume to
>> > occur at this time. The barrier wouldn't prevent that.
>> >
>> > It's unlikely, I agree, but not impossible.
>>
>> Yeah, I didn't think about that.
>
> Come to think of it, if the hardware sends a wakeup request then it
> must have been enabled for remote wakeup. And if the hardware settings
> are appropriate for system suspend then it must be enabled for system
> wakeup. Consequently a wakeup from the hardware ought to abort the
> system suspend in any case. So maybe we don't care about this
> scenario.
>
> On the other hand, there may be other mechanisms that could cause a
> runtime resume at this inconvenient time. A timer routine, for
> instance.
Another common case is when device X depends on device Y in it's
->prepare or ->suspend path (e.g. need to write to an I2C connected
GPIO/PMIC) in which case, device Y (and the I2C bus) would be runtime
resumed during device X's ->prepare or ->suspend path, and possibly
after device Y (or the I2C busses) ->prepare and ->suspend.
Kevin
next prev parent reply other threads:[~2014-05-15 17:35 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 [this message]
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
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
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