From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [PATCH 0/8] Suspend block api (version 6)
Date: Sun, 16 May 2010 01:51:09 +0200
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To: Brian Swetland <swetland@google.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>, Jesse Barnes <jbarnes@virtuousgeek.org>, linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, Arjan van de Ven <arjan@infradead.org>, Matthew Garrett <mjg@redhat.com>, Len Brown <len.brown@intel.com>, Jacob Pan <jacob.jun.pan@linux.intel.com>, Oleg Nesterov <oleg@redhat.com>, Liam Girdwood <lrg@slimlogic.co.uk>, linux-omap@vger.kernel.org, Linus Walleij <linus.walleij@stericsson.com>, Daniel Walker <dwalker@codeaurora.org>, Theodore Ts'o <tytso@mit.edu>, Mark Brown <broonie@opensource.wolfsonmicro.com>, Geoff Smith <geoffx.smith@intel.com>, Tejun Heo <tj@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Wu Fengguang <fengguang.wu@intel.com>
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On Saturday 15 May 2010, Brian Swetland wrote:
> On Sat, May 15, 2010 at 12:47 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> >> >
> >> > Yes, "excruciatingly bad" apps can kill PM on these systems since
> >> > anyone can write apps, but the same is true on an opporunistic-suspend
> >> > based system since any app could hold a suspend blocker whenever it
> >> > wants.
> >>
> >> No, apps need permission to block suspend.
> >
> > Are you referring to the fact the permissions of the special device file or
> > something different?
> 
> The special device file will have filesystem permissions that limit
> access to system services.
> 
> Arbitrary userspace apps do not have direct access to the device --
> they use a service (provided by binder rpc), and the app must declare
> its intent (and the user accept this on install) in order to use that
> service.

On Android, right?

> The service keeps track of usage stats so if a user
> experiences poor battery life they can look at the battery usage thing
> and see which apps are keeping the device awake, etc.

That sounds like it should go into a doc or at least into the changelog of
patch [2/8] IMnsHO.

The thing you said about timers in one of the previous messages should be
documented too, BTW, because it's one of the motivation factors for this
work.

In general, I think the motivation is not explained sufficienty in the patches'
changelogs and that's one of the reasons why people have so many doubts about
the feature's usefulness.

Thanks,
Rafael