From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DBD8C282D7 for ; Wed, 30 Jan 2019 10:27:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E2C222175B for ; Wed, 30 Jan 2019 10:27:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="JWnkyXea"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="m3YtD2Pv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730502AbfA3K1j (ORCPT ); Wed, 30 Jan 2019 05:27:39 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:59230 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727752AbfA3K1i (ORCPT ); Wed, 30 Jan 2019 05:27:38 -0500 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id C449F60D02; Wed, 30 Jan 2019 10:27:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1548844057; bh=xeFbAGv+R+EEpUiVr3bBHr5qEmeuBaUllI1G1umJIxo=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=JWnkyXeai0tPpFLQjXd/O6MmUN5KWSSSLfkaOdfvUQN6xDYuXi4+WiwK2J3fL8SNh BEh/CmS2tKqZ64maVoIQZWCP4l76S9FnWl6BtmmOXUnBOKmyQ+LPlmm6Vy3zcGOa70 WLqo/+fDhEwNTl/IZJ6W3g9rOLyPmbbtMSL4j3V4= Received: from potku.adurom.net (88-114-240-156.elisa-laajakaista.fi [88.114.240.156]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: kvalo@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 8C5ED60C69; Wed, 30 Jan 2019 10:27:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1548844056; bh=xeFbAGv+R+EEpUiVr3bBHr5qEmeuBaUllI1G1umJIxo=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=m3YtD2PvjxZIqEx5lPDyu9K0kb/yNK67bN1b43N6BStqgW5KCZANIh2kBCGM4Uodm 7YFJ1ixmszdpYq/eA81lmx24zF6qok0ZB9QAJYE//QsMUdvte8aqAVc1pXPmrqfnDy UCtMLYOoXPzq7G52KEw3psS+cVhgGSxT9xPeyIfw= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 8C5ED60C69 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=kvalo@codeaurora.org From: Kalle Valo To: Stanislaw Gruszka Cc: Felix Fietkau , linux-wireless@vger.kernel.org, Lorenzo Bianconi Subject: Re: [PATCH v2 0/7] mt76x02: Beacon support for USB References: <1548678108-9526-1-git-send-email-sgruszka@redhat.com> <87a7jju1mv.fsf@purkki.adurom.net> <8ec3b133-49eb-3c5f-4c3c-bc2bb4e84cde@nbd.name> <87k1inwtu5.fsf@codeaurora.org> <20190130082937.GA2720@redhat.com> Date: Wed, 30 Jan 2019 12:27:33 +0200 In-Reply-To: <20190130082937.GA2720@redhat.com> (Stanislaw Gruszka's message of "Wed, 30 Jan 2019 09:29:39 +0100") Message-ID: <87fttal9t6.fsf@kamboji.qca.qualcomm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Stanislaw Gruszka writes: > On Tue, Jan 29, 2019 at 01:10:08PM +0100, Felix Fietkau wrote: >> On 2019-01-29 13:07, Kalle Valo wrote: >> > Felix Fietkau writes: >> > >> >> On 2019-01-29 12:47, Kalle Valo wrote: >> >>> Stanislaw Gruszka writes: >> >>> >> >>>> We can configure beaconing, but without TBTT interrupt we >> >>>> can not support PS buffering. This can be added later using >> >>>> kernel hrtimer, if we can keep it in sycn with device timer. >> >>>> >> >>>> I tested AP and IBSS modes. >> >>> >> >>> So how does this work reliably so that there's no packet loss with >> >>> clients using power save? >> >> >> >> There will be multicast packet loss for clients using power save. >> > >> > Isn't that a problem? At least as a normal user I would very frustrated >> > if sometimes my connection work and sometimes not, for example if I'm >> > trying discover devices from my network. Hopefully nobody won't use USB >> > devices for any real AP stuff, but still enabling something which we >> > know doesn't work realiably is concerning. >> I agree. Maybe we should leave out the flag for AP mode in this patch >> until we have PS buffering and leave the rest of the code intact. > > But how serious problem of dropping multicast frames for PS stations > is? It's _both_ broadcast and multicast frames. Felix already mentioned ARP but there are also other protocols which rely on broadcast/multicast frames. > I don't think from user perspective this is "sometimes my connection > work and sometimes not", but something much less annoying. So basically you are saying that we should just depend on lock and hope that users don't notice the packet loss. I don't think that's really good design philosophy. > Moreover in the tree we have already bunch of drivers that do > advertise AP mode support without HOST_BROADCAST_PS_BUFFERING > like iwlwifi or brcm80211 . After seeing how much those drivers are tested I would be very surprised to see that their broadcast and multicast packet handling is broken. > So I don't think we should drop AP flag, AP mode works with > this patch set quite well. "Works" is a very broad statement and depends on what you have tested. Sure, if you tested tested with ping and iperf from a client to AP without using power save mode that will work. But if you try to connect from another device on the network to another client using aggressive power saving it's a totally different situation. Back in the Nokia N800 days I wasted a lot of time debugging all sort of buggy APs which didn't work correctly with power save, it was really annoying and very frustrating for the users. Let's not do the same mistakes, we are better than that. -- Kalle Valo