linux-kernel - Re: [RFC][PATCH 2/3] PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 15 May 2014 14:06:59 +0200
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Alan Stern <stern@...land.harvard.edu>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Linux PM list <linux-pm@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Aaron Lu <aaron.lu@...el.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Kevin Hilman <khilman@...aro.org>
Subject: Re: [RFC][PATCH 2/3] PM / sleep: Mechanism to avoid resuming
 runtime-suspended devices unnecessarily

> Do we want to allow ->prepare() to return > 0 if the device isn't
> runtime suspended?  If we do then non-suspended devices may be a common
> case.  We should then avoid the extra overhead of disable + enable.
> So I would write:
>
>         if (dev->power.direct_complete) {
>                 if (pm_runtime_status_suspended(dev)) {
>                         pm_runtime_disable(dev);
>                         if (dev->power.disable_depth == 1
>                             && pm_runtime_status_suspended(dev))
>                                 goto Complete;
>                         pm_runtime_enable(dev);
>                 }
>                 dev->power.direct_complete = false;
>         }
>

I am wondering whether the above pm_runtime_disable|enable actually
belongs better in driver/subsystem in favour of the PM core?

Doesn't the driver/subsystem anyway needs to be on top of what goes
on? Typically, while runtime PM has been disabled, that might affect
it's wakeup handling? Or this case are already handled due to other
circumstances?

Kind regards
Ulf Hansson
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/