linux-kernel - Re: [PATCH 0/8] Suspend block api (version 6)

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Date:	Fri, 7 May 2010 03:57:37 -0700
From:	Arve Hjønnevåg <arve@...roid.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Brian Swetland <swetland@...gle.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Matthew Garrett <mjg@...hat.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Kevin Hilman <khilman@...prootsystems.com>,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	Tejun Heo <tj@...nel.org>, Oleg Nesterov <oleg@...hat.com>,
	Paul Walmsley <paul@...an.com>, magnus.damm@...il.com,
	mark gross <mgross@...ux.intel.com>,
	Arjan van de Ven <arjan@...radead.org>,
	Geoff Smith <geoffx.smith@...el.com>, rebecca@...roid.com
Subject: Re: [PATCH 0/8] Suspend block api (version 6)

2010/5/7 Mark Brown <broonie@...nsource.wolfsonmicro.com>:
> On Wed, May 05, 2010 at 09:25:18PM -0700, Arve Hjønnevåg wrote:
>> On Wed, May 5, 2010 at 4:40 PM, Mark Brown
>
>> > This really does depend heavily on system design and the intended
>> > function of the suspend on the part of the initiator.  In many systems
>> > suspend will remove sufficient power to stop audio running even if it
>> > were desired, and there's the idea with existing manually initiated
>> > suspends that the system should stop what it's doing and go into a low
>> > power, low responsiveness state.  Some systems will initiate a suspend
>> > with active audio paths (especially those to or from the AP) which they
>> > expect to be stopped.
>
>> You can support both in the same driver in some cases (without a
>> switch). If the hardware cannot wake the system when it needs more
>> audio buffers, then the driver needs to block suspend while audio is
>> playing. Since suspend blockers only block opportunistic suspend, the
>> driver can also implement suspend to stop audio playback and it will
>> only be called for forced suspend.
>
> As discussed elsewhere in the thread a suspend blocker is not desirable
> here - the AP is not doing anything useful on a voice call so blocking
> the suspend will just waste power unless runtime PM is good enough to
> mean opportunistic suspend isn't adding anything anyway.  It will avoid
> the immediate issue with loosing audio but it's not really what we want
> to happen.
>

I was talking about audio from the AP. Why would you ever turn off
another core's audio path on suspend?

-- 
Arve Hjønnevåg
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