Return-path: Received: from mail-qy0-f181.google.com ([209.85.216.181]:36086 "EHLO mail-qy0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755001Ab1BBTJD (ORCPT ); Wed, 2 Feb 2011 14:09:03 -0500 Received: by qyk12 with SMTP id 12so319612qyk.19 for ; Wed, 02 Feb 2011 11:09:02 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <874o8mbaec.fsf@purkki.adurom.net> References: <201101311600.39486.IvDoorn@gmail.com> <874o8mbaec.fsf@purkki.adurom.net> Date: Wed, 2 Feb 2011 20:09:02 +0100 Message-ID: Subject: Re: [RFC] rt2x00: Add autowakeup timer for receiving beacons while in powersave mode From: Ivo Van Doorn To: Kalle Valo Cc: users@rt2x00.serialmonkey.com, linux-wireless@vger.kernel.org, RA-Jay Hung , RA-Dennis Lee , RA-Eddy Tsai Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi, >> Add a delayed work structure which can be used to wakeup the device >> just before a beacon from the AP is expected. This then allows the >> device to receive the beacon, check if there are pending broadcast >> or multicast frames. > > So the firmware/hardware doesn't have support for tracking and waking > up for beacons? I didn't even know that such hardware exists :) Waking > up for beacons from host sounds very inefficient and unrealiable. All > the devices I have seen either do this in firmware or hardware due to > time constraints. Even at76c50x-usb, which is ancient, does all this > in firmware. > > Are you sure there's no way to do this with hardware? Well the official Ralink driver also uses a timer to wakeup the hardware, there are however registers which suggest support for autowake functionality. Jay, Dennis, Eddy, can you explain a but how the autowake functionality is implemented in the rt2800usb firmware? >> TODO: Split out mac80211 changes into a separate patch. We also need >> to know if we need this check in mac80211 or in the driver. >> Personally I think the check belongs in mac80211, but at this time >> that work has been deferred to the drivers. However this means that >> a lot of logic is needed in the driver to check if the correct IE is >> available, and then check the value, while mac80211 will obtains >> that exact IE anyway during RX processing anyway... > > I'm worried that client power save support in mac80211 is getting > quite complex already. How many drivers need this feature? At least rt2800usb and carl9170. But I haven't done a full round through all drivers though. Ivo