Return-path: Received: from mu-out-0910.google.com ([209.85.134.189]:9145 "EHLO mu-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752599AbYLBM7A (ORCPT ); Tue, 2 Dec 2008 07:59:00 -0500 Received: by mu-out-0910.google.com with SMTP id g7so2543924muf.1 for ; Tue, 02 Dec 2008 04:58:57 -0800 (PST) Message-ID: <8e92b4100812020458l29d96527g71bf9f5fb9a5993@mail.gmail.com> (sfid-20081202_135911_063096_D77D54E7) Date: Tue, 2 Dec 2008 18:28:57 +0530 From: "Vivek Natarajan" To: "Tomas Winkler" Subject: Re: [RFC] mac80211: Enhancements to dynamic power save. Cc: "Kalle Valo" , "Johannes Berg" , "Vivek Natarajan" , linux-wireless@vger.kernel.org In-Reply-To: <1ba2fa240812010900t4781aca2uc33bc26bc1ef161@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 References: <20081202011754.GA9382@myhost.users.atheros.com> <1228133121.3478.27.camel@johannes.berg> <873ah76fax.fsf@nokia.com> <1ba2fa240812010900t4781aca2uc33bc26bc1ef161@mail.gmail.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: Tomas Winkler wrote: > On Mon, Dec 1, 2008 at 6:17 PM, Kalle Valo wrote: >> Johannes Berg writes: >> >>> On Mon, 2008-12-01 at 17:17 -0800, Vivek Natarajan wrote: >>>> This patch is based on Kalle's initial RFC patches on dynamic power save. >>>> Since ath9k/ath5k,stlc45xx and b43 need the driver to send the null >>>> frame, it is appropriate to do it from mac80211. >>>> This patch enables mac80211 to send a null frame and also to >>>> check for tim in the beacon if power save is enabled. >>> >>> One thing I forgot, do we need a special iwlwifi flag to turn this off? >>> Or can iwlwifi be programmed to let the host handle this (*), which >>> might be beneficial for interoperability and uniformity purposes? >> >> Having the null frame handling in firmware is faster and we might get >> some power savings from that. But is the saving observable, that's an >> another question :) > > This patch is not much relevant in actual saving , since this is the > waking up part, you are powering the whole nic up anyway. I agree but with PM bit on-off, this is what one can do to reduce some power consumption although not significant. If more significant savings is needed, we may need to implement PS-POLL or the APSD mechanism. But this is a good start to power save in mac80211. > The firmware handling of power save is more relevant in going to sleep > phase and sustaining where decision about sending the null frame is > faster then from host. The NIC is powered down in stages up to state > where only slow clock is ticking so this is rather time sensitive AFAIK, only iwlwifi has this firmware support and we need mac80211's support in this for ath9k/ath5k,stlc45xx and b43. I believe a powerful 2GHz host processor can manage these timings as a Windows driver for these vendor cards seems to support power save without firmware support. -- Vivek.