Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752914AbdC0QVz convert rfc822-to-8bit (ORCPT ); Mon, 27 Mar 2017 12:21:55 -0400 Received: from out.consiagnet.it ([83.149.128.196]:23618 "EHLO out.consiagnet.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752178AbdC0QVl (ORCPT ); Mon, 27 Mar 2017 12:21:41 -0400 X-Spam-Flag: NO X-Spam-Score: -2.901 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 10.2 \(3259\)) Subject: Re: [PATCH] usb-musb: keep VBUS on when device is disconnected From: Moreno Bartalucci In-Reply-To: <20170327143049.GG10760@atomide.com> Date: Mon, 27 Mar 2017 18:20:29 +0200 Cc: Bin Liu , Lars Melin , "linux-omap@vger.kernel.org" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Alessio Igor Bogani Content-Transfer-Encoding: 8BIT Message-Id: <63FD9E13-2B70-485C-80A7-206BEC16905A@tecnorama.it> References: <20170315140801.97230-1-moreno.bartalucci@tecnorama.it> <20170324185836.GC19814@uda0271908> <2d10809f-d482-ffa9-30b7-8785e94ab102@gmail.com> <00882633-3F61-4010-A4D2-D04473282B10@tecnorama.it> <20170327131701.GA12674@uda0271908> <20170327143049.GG10760@atomide.com> To: Tony Lindgren X-Mailer: Apple Mail (2.3259) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1083 Lines: 29 > Il giorno 27 mar 2017, alle ore 16:30, Tony Lindgren ha scritto: > > […] > I wonder if the following test patch allows the mode changing > devices to been properly found? Of course it's just for testing, > and scanning for devices takes now 5 seconds.. But it might > provide clues why musb thinks no devices are connected and we > cut VBUS. > > […] Hi Tony, thanks for your patch. I tested it with both current mainline kernel and my “production” kernel (4.9.13): they have the same behaviour. During boot, vbus is first asserted, then removed for a slightly longer time than before (most likely 5 seconds now), then reasserted. When my device is mode-switched, it is working properly with your patch. If I understood your patch, however, if the device (anyone, not just my one) takes longer to switch, VBUS is deasserted anyway. Although this patch is working for me, personally I would prefer a solution which would not deassert VBUS. At least on a host only port. Honestly I don’t know how a dual role port should work. Regards, Moreno