From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtprelay2.synopsys.com ([198.182.60.111]:60530 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752777AbcDKV2K (ORCPT ); Mon, 11 Apr 2016 17:28:10 -0400 Subject: Re: usb: gadget: composite: Return bcdUSB 0x0310 To: Greg Kroah-Hartman , John Youn References: <57083C8C.8000804@synopsys.com> <20160409005814.GA27479@kroah.com> From: John Youn CC: "stable@vger.kernel.org" , Felipe Balbi Message-ID: <570C16E8.9070001@synopsys.com> Date: Mon, 11 Apr 2016 14:28:08 -0700 MIME-Version: 1.0 In-Reply-To: <20160409005814.GA27479@kroah.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org List-ID: On 4/8/2016 5:58 PM, Greg Kroah-Hartman wrote: > On Fri, Apr 08, 2016 at 04:19:40PM -0700, John Youn wrote: >> Hi, >> >> I'd like to request the following be applied to stable trees 3.2+. >> >> 1a85329171094951956a37acc8abb7e51c1e742e ("usb: gadget: composite: >> Return bcdUSB 0x0310") >> >> The USB 3.1 specification replaces the USB 3.0 specification and all new >> devices that are running at SuperSpeed or higher speeds must report a >> bcdUSB of 0x0310. > > That doesn't seem very "backwards compatible" of the spec to me, what > happens if you return a 3.0 string, when you really are only handling > 3.0 things like we do in older kernels? > > thanks, > > greg k-h > Hi Greg, I believe there would be no backward-incompatible change as all 3.0 things are now part of the 3.1 spec, and the new stuff in 3.1 (such as SuperSpeedPlus) are exposed through new descriptors. And I don't believe anything currently looks at bcdUSB 3.0 vs 3.1 (unlike with USB 2.x). But I can't say for sure. This is only needed because the CV tool has started requiring this and I believe the compliance process will also start requiring it for all new devices. We plan to certify new devices with kernels as old as 3.18, hence this backport. If you like, I can solicit comments on this from the linux-usb list. Thanks, John