From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: UAS: fix alignment of scatter/gather segments From: Oliver Neukum Message-Id: <1556557130.20085.24.camel@suse.com> Date: Mon, 29 Apr 2019 18:58:50 +0200 To: Alan Stern Cc: David Laight , "gregKH@linuxfoundation.org" , "linux-usb@vger.kernel.org" List-ID: T24gTW8sIDIwMTktMDQtMjkgYXQgMTI6MDggLTA0MDAsIEFsYW4gU3Rlcm4gd3JvdGU6Cj4gT24g TW9uLCAyOSBBcHIgMjAxOSwgT2xpdmVyIE5ldWt1bSB3cm90ZToKPiAKPiA+IE9uIE1vLCAyMDE5 LTA0LTI5IGF0IDE1OjA2ICswMDAwLCBEYXZpZCBMYWlnaHQgd3JvdGU6Cj4gCj4gPiBCdXQgdGhl IHN0YXRlbWVudCB0aGUgb2xkIGNvbW1lbnQgbWFkZSBhcmUgbm8gbG9uZ2VyIGNvcnJlY3QuCj4g Cj4gUGVyaGFwcyBEYXZpZCB3b3VsZCBiZSBzYXRpc2ZpZWQgaWYgdGhlIGNvbW1lbnQgd2VyZSBj aGFuZ2VkIHRvIHNheSAKPiB0aGF0IF9zb21lXyBVU0IgY29udHJvbGxlciBkcml2ZXJzIGhhdmUg dGhpcyB1bnVzdWFsIGFsaWdubWVudCAKPiByZXF1aXJlbWVudC4KCkl0IHdvdWxkIHNlZW0gdG8g bWUgdGhhdCBldmVyeSBjb250cm9sbGVyIHRoYXQgZG9lcyBub3QgZG8Kc2NhdHRlci9nYXRoZXIg aGFzIHRoaXMgcmVxdWlyZW1lbnQuIEluIG90aGVyIHdvcmRzLCB0aGlzIGlzCnRoZSB0cnVlIHJl cXVpcmVtZW50IG9mIFVTQi4gSXQgZG9lcyBub3QgY29tZSBmcm9tIHRoZQpjb250cm9sbGVyLiBJ dCBjb21lcyBmcm9tIHRoZSBwcm90b2NvbCdzIG5lZWQgdG8gbm90CnNlbmQgYSBzaG9ydCBwYWNr YWdlLgoKVGhlIHNlY29uZCwgb2xkLCBjb21tZW50IGlzIGFib3V0IGNvbnRyb2xsZXJzLgoKCVJl Z2FyZHMKCQlPbGl2ZXIK 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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 80317C43219 for ; Mon, 29 Apr 2019 16:59:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58A8A2087B for ; Mon, 29 Apr 2019 16:59:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728859AbfD2Q7H (ORCPT ); Mon, 29 Apr 2019 12:59:07 -0400 Received: from mx2.suse.de ([195.135.220.15]:53826 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728681AbfD2Q7H (ORCPT ); Mon, 29 Apr 2019 12:59:07 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 3D677ABC7; Mon, 29 Apr 2019 16:59:06 +0000 (UTC) Message-ID: <1556557130.20085.24.camel@suse.com> Subject: Re: [PATCH] UAS: fix alignment of scatter/gather segments From: Oliver Neukum To: Alan Stern Cc: David Laight , "gregKH@linuxfoundation.org" , "linux-usb@vger.kernel.org" Date: Mon, 29 Apr 2019 18:58:50 +0200 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Message-ID: <20190429165850.lJi1I6d1n0fghwvupKim8OQ57e9OLiORARWNOniUx4I@z> On Mo, 2019-04-29 at 12:08 -0400, Alan Stern wrote: > On Mon, 29 Apr 2019, Oliver Neukum wrote: > > > On Mo, 2019-04-29 at 15:06 +0000, David Laight wrote: > > > But the statement the old comment made are no longer correct. > > Perhaps David would be satisfied if the comment were changed to say > that _some_ USB controller drivers have this unusual alignment > requirement. It would seem to me that every controller that does not do scatter/gather has this requirement. In other words, this is the true requirement of USB. It does not come from the controller. It comes from the protocol's need to not send a short package. The second, old, comment is about controllers. Regards Oliver