From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?utf-8?Q?Bj=C3=B8rn_Mork?= Subject: Re: [PATCH RFC 1/1] usb: Tell xhci when usb data might be misaligned Date: Thu, 30 Jan 2014 23:05:22 +0100 Message-ID: <87bnytqg65.fsf@nemi.mork.no> References: <20140130211816.GB3787@xanatos> <20140130215523.GC14228@xanatos> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Alan Stern , David Laight , "linux-usb\@vger.kernel.org" , "netdev\@vger.kernel.org" , Greg Kroah-Hartman , David Miller , Dan Williams , "Nyman\, Mathias" , Mark Lord , Freddy Xin To: Sarah Sharp Return-path: Received: from canardo.mork.no ([148.122.252.1]:39820 "EHLO canardo.mork.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753226AbaA3WFs convert rfc822-to-8bit (ORCPT ); Thu, 30 Jan 2014 17:05:48 -0500 In-Reply-To: <20140130215523.GC14228@xanatos> (Sarah Sharp's message of "Thu, 30 Jan 2014 13:55:23 -0800") Sender: netdev-owner@vger.kernel.org List-ID: Sarah Sharp writes: > On Thu, Jan 30, 2014 at 04:43:54PM -0500, Alan Stern wrote: > >> ehci-hcd gets along okay with the restriction that each SG element=20 >> except the last has to be a multiple of the maxpacket size. xhci-hc= d=20 >> can relax this quite a lot, but not all the way. > > What does the EHCI driver do when it receives a SG list from the USB > networking layer that violates this restriction? The USB networking layer won't use SG with the EHCI driver. Commit bcc48f1a7a0d4 introduced no_sg_constraint so that usbnet could enable SG only for host controllers with no such restrictions. I.e. currently for xHCI only. Bj=C3=B8rn