Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760707Ab0HFIJS (ORCPT ); Fri, 6 Aug 2010 04:09:18 -0400 Received: from mail.lang.hm ([64.81.33.126]:58828 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755872Ab0HFIJJ (ORCPT ); Fri, 6 Aug 2010 04:09:09 -0400 Date: Fri, 6 Aug 2010 01:07:47 -0700 (PDT) From: david@lang.hm X-X-Sender: dlang@asgard.lang.hm To: Brian Swetland cc: paulmck@linux.vnet.ibm.com, kevin granade , =?ISO-8859-15?Q?Arve_Hj=F8nnev=E5g?= , Matthew Garrett , "Rafael J. Wysocki" , Arjan van de Ven , linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, pavel@ucw.cz, florian@mickler.org, stern@rowland.harvard.edu, peterz@infradead.org, tglx@linutronix.de, alan@lxorguk.ukuu.org.uk Subject: Re: Attempted summary of suspend-blockers LKML thread In-Reply-To: Message-ID: References: <20100805004802.GP24163@linux.vnet.ibm.com> <20100805151211.GA10080@linux.vnet.ibm.com> <20100805203102.GN2447@linux.vnet.ibm.com> <20100805230304.GQ2447@linux.vnet.ibm.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="680960-1185624910-1281082068=:30564" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2477 Lines: 55 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --680960-1185624910-1281082068=:30564 Content-Type: TEXT/PLAIN; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8BIT On Thu, 5 Aug 2010, Brian Swetland wrote: > On Thu, Aug 5, 2010 at 6:01 PM, wrote: >> On Thu, 5 Aug 2010, Brian Swetland wrote: >>> On Thu, Aug 5, 2010 at 5:16 PM,   wrote: >>>>>> >>>>>> So for an mp3 playback, does an Android suspend between data fetches? >>>>> >>>>> It can if the latency is long enough (which is why I point out low >>>>> power audio which is usually high latency).  For low latency (system >>>>> sounds, etc) 10-25ms between buffers it's not practical to fully >>>>> suspend but we will go to the lowest power state in idle if possible. >>>> >>>> the playback is able to continue even with all the clocks stopped? that >>>> surprises me. I would hav expected it to be able to sleep while playing >>>> audio, but not do a full suspend. >>> >>> Obviously not all clocks are stopped (the DSP and codec are powered >>> and clocked, for example), but yeah we can clock gate and power gate >>> the cpu and most other peripherals while audio is playing on a number >>> of ARM SoC designs available today (and the past few years). >> >> does this then mean that you have multiple variations of suspend? >> >> for example, one where the audio stuff is left powered, and one where it >> isn't? > > While the cpu (and the bulk of the system) is suspended, it's not > uncommon for some peripherals to continue to operate -- for example a > cellular radio, gps, low power audio playback, etc. Details will vary > depending on the SoC and board design. It's not so much a different > suspend mode (the system is still suspended), just a matter of whether > a peripheral can operate independently (and if it is lower power for > it to do so). this helps, but isn't quite what I was trying to ask. on a given piece of hardware, does suspend always leave the same peripherals on, or do you sometimes power more things down than other times when suspending? David Lang --680960-1185624910-1281082068=:30564-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/