From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-vw0-f192.google.com ([209.85.212.192]:63793 "EHLO mail-vw0-f192.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755669AbZKYJuQ (ORCPT ); Wed, 25 Nov 2009 04:50:16 -0500 Received: by vws30 with SMTP id 30so2076425vws.33 for ; Wed, 25 Nov 2009 01:50:22 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <87zl6b9f0i.fsf@purkki.valot.fi> References: <1259132754-18164-1-git-send-email-vnatarajan@atheros.com> <87zl6b9f0i.fsf@purkki.valot.fi> Date: Wed, 25 Nov 2009 15:20:22 +0530 Message-ID: <8e92b4100911250150p31f3d0dr6cdace01ff8c55a5@mail.gmail.com> Subject: Re: [RFC PATCH] mac80211: Send null data frame after disabling power save in Tx path. From: Vivek Natarajan To: Kalle Valo Cc: Vivek Natarajan , linux-wireless@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, Nov 25, 2009 at 2:07 PM, Kalle Valo wrote: > Vivek Natarajan writes: > >> For drivers setting IEEE80211_HW_PS_NULLFUNC_STACK, a null data frame >> with PM bit off has to be sent before sending normal data frames. > > Why? Sending a data frame with PM bit off should be enough to inform > AP that the client is awake. Since the subtype is different for null function data frame (IEEE80211_STYPE_NULLFUNC) which is normally used to indicate the power management status , than normal data frame (IEEE80211_STYPE_DATA), I thought some APs might create some functionality issues by checking the frame subtype. After your mail, I looked at the spec and it does not mention about null frame in this context. It says, 'STAs changing Power Management mode shall inform the AP of this fact using the Power Management bits within the Frame Control field of transmitted frames. ' Accordingly, the present implementation might be correct. Thanks for pointing it out. Vivek.