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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT 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 93333C31E46 for ; Wed, 12 Jun 2019 12:28:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7405020874 for ; Wed, 12 Jun 2019 12:28:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406351AbfFLM2x (ORCPT ); Wed, 12 Jun 2019 08:28:53 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:40107 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729008AbfFLM2x (ORCPT ); Wed, 12 Jun 2019 08:28:53 -0400 Received: by mail-wr1-f68.google.com with SMTP id p11so16706941wre.7 for ; Wed, 12 Jun 2019 05:28:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=wOI50hz2miBWNTk9p+QKCu63hJI9jM//4084I5DdVT4=; b=Kc3NqlZ/d9KGUUoX0anSvThsXcds6fx1qHbYFqU3G27jpvMhMZnCriA3ULAn7H0eq/ UTb07+pBVnN8IkK4QHZXLWEoeLW92yQ+Y8lQVzehnEMYRvN/rxoI/ZhS6u7PZSvO5TsS pKBeJiD9dOQWxzYVyaCMpq6sSvXQaRXbof8QIFcFpyLKPjlFyoH+sR7b+1K6qyNtuKQy QUEHJkxOnboTa2jxonUDP8AgmLVh76/9y4jotaITXivik1EGTGFl9DLHKH5+jrU/6lu6 SgsYCHrA/ilo8PRN3uXwJOu+PCevS42pNCYzAuLZc3+KPh+iiLdYqqAwj0EWvnjyCuCd VP0Q== X-Gm-Message-State: APjAAAUi0bNyKFgzLcSIN5jsg57e0T6N1J9BMDRK1wrYBk2Lyd/DGjBW NVkry1ohBuq1aR6q295i/lakQQ== X-Google-Smtp-Source: APXvYqzPZJ1AKIXvFNuQkNHYgJgSoOJBnCkksffkpptFJdFyb/sNEre45JFukWJyXL1X6G4T7qpCFA== X-Received: by 2002:adf:ff84:: with SMTP id j4mr28488817wrr.151.1560342531399; Wed, 12 Jun 2019 05:28:51 -0700 (PDT) Received: from localhost.localdomain (nat-pool-mxp-t.redhat.com. [149.6.153.186]) by smtp.gmail.com with ESMTPSA id v13sm3470434wmj.46.2019.06.12.05.28.50 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 12 Jun 2019 05:28:50 -0700 (PDT) Date: Wed, 12 Jun 2019 14:28:48 +0200 From: Lorenzo Bianconi To: Stanislaw Gruszka Cc: Lorenzo Bianconi , nbd@nbd.name, kvalo@codeaurora.org, linux-wireless@vger.kernel.org Subject: Re: [PATCH v2 2/2] mt76: usb: do not always copy the first part of received frames Message-ID: <20190612122845.GH8107@localhost.localdomain> References: <2ed0b595a12944a8cfea14e066bcc4fa24f0ba44.1559293385.git.lorenzo@kernel.org> <20190612091036.GB2965@redhat.com> <20190612095302.GD8107@localhost.localdomain> <20190612102502.GB4431@redhat.com> <20190612104921.GF8107@localhost.localdomain> <20190612115120.GA3496@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="+QwZB9vYiNIzNXIj" Content-Disposition: inline In-Reply-To: <20190612115120.GA3496@redhat.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org --+QwZB9vYiNIzNXIj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable [...] >=20 > My sense of humor declined quite drastically lastly ;-/ >=20 > > > > but we can be more cautious since probably copying > > > > the first 128B will not make any difference > > >=20 > > > Not sure if I understand what you mean. > >=20 > > Please correct me if I am wrong but I think max amsdu rx size is 3839B = for > > mt76. For the sg_en case this frame will span over multiple sg buffers = since > > sg buffer size is 2048B (2 sg buffers). Moreover if we do not take into= account > > skb_shared_info when configuring the sg buffer size we will need to alw= ays copy > > the first 128B of the first buffer since received len will be set to 20= 48 and > > the following if condition will always fail: > >=20 > > if (SKB_WITH_OVERHEAD(buf_size) >=3D MT_DMA_HDR_LEN + len) { > > } >=20 > Ok, that I understand. >=20 > > > > > And skb_shered_info is needed only in first buffer IIUC. > > > > >=20 > > > > > Also this patch seems to make first patch unnecessary except for > > > > > non sg_en case (in which I think rx AMSDU is broken anyway), > > > > > so I would prefer just to apply first patch. > > > >=20 > > > > I do not think rx AMSDU is broken for non sg_en case since the max = rx value > > > > allowed should be 3839 IIRC and we alloc one page in this case > > >=20 > > > If that's the case we should be fine, but then I do not understand > > > why we allocate 8*2k buffers for sg_en case, isn't that AP can > > > sent AMSDU frame 16k big? > >=20 > > Sorry I did not get what you mean here, could you please explain? >=20 > If max RX AMSDU size is 3839B I do not see reason why we allocate > MT_SG_MAX_SIZE=3D8 of MT_RX_BUF_SIZE=3D2k buffers for sg_en case. > I thought the reason is that max AMSDU size is 16kB so it fit into > 8 sg buffers of 2k. >=20 > In other words, for me, looks like either > - we can not handle AMSDU for non sg case because we do not > allocate big enough buffer I think AMSDU is mandatory and we currently support it even for non-sg case (since max rx AMSDU is 3839B) > or > - we can just use one PAGE_SIZE buffer for rx and remove sg > buffers for rx completely=20 using sg buffers we can support bigger rx AMSDU size in the future without = using huge buffers (e.g. we can try to use IEEE80211_MAX_MPDU_LEN_HT_7935 with mt76x2u) Regards, Lorenzo >=20 > Do I miss something ? >=20 > Stanislaw --+QwZB9vYiNIzNXIj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCXQDv+gAKCRA6cBh0uS2t rIZVAQDOX/3izMO+2QI5CgHjot8A94v5ougnMh8SCC6TigbznAEAuSvrnfKDj8uf 5lZ1Ai68Xsw3Fe3K/jj83MyrJKoyXgw= =vTVV -----END PGP SIGNATURE----- --+QwZB9vYiNIzNXIj--