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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D842C433EF for ; Wed, 8 Dec 2021 02:52:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234803AbhLHC4B (ORCPT ); Tue, 7 Dec 2021 21:56:01 -0500 Received: from netrider.rowland.org ([192.131.102.5]:38877 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S234660AbhLHC4B (ORCPT ); Tue, 7 Dec 2021 21:56:01 -0500 Received: (qmail 557419 invoked by uid 1000); 7 Dec 2021 21:52:29 -0500 Date: Tue, 7 Dec 2021 21:52:29 -0500 From: Alan Stern To: Thinh Nguyen Cc: "linux-usb@vger.kernel.org" , Hans de Goede , Greg Kroah-Hartman Subject: Re: Why no SG support for isoc Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, Dec 07, 2021 at 10:24:41PM +0000, Thinh Nguyen wrote: > Hi, > > I came across this change fe2072cc1768 ("usb/hcd: Ensure scatter-gather > is not used for isoc transfers") and wonder why it was made. The > description doesn't explain much. I was trying to look for the archived > conversation about this but couldn't find it. > > Can someone help explain why we enforce this to all hosts? Or help point > to the archived conversation with the full explanation? I don't remember the details; it was nine years ago. However, you can find the email thread for the original patch submission here: https://marc.info/?t=134122051600006&r=1&w=2 The discussion leading up to it apparently started here: https://marc.info/?l=linux-usb&m=134098509628768&w=2 Alan Stern