From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Date: Mon, 27 Mar 2017 09:59:47 -0700 Message-ID: <20170327165946.GL10760@atomide.com> 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> <63FD9E13-2B70-485C-80A7-206BEC16905A@tecnorama.it> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <63FD9E13-2B70-485C-80A7-206BEC16905A-Hj/TeGiWV4YL5bzFcGmneg@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Moreno Bartalucci Cc: Bin Liu , Lars Melin , "linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Alessio Igor Bogani List-Id: linux-omap@vger.kernel.org * Moreno Bartalucci [170327 09:23]: > If I understood your patch, however, if the device (anyone, not just my one) takes longer to switch, VBUS is deasserted anyway. Yeah some of them can take at least 10 seconds even to enumerate. So probably we need to have to have some longer timeout set for OTG_STATE_A_WAIT_BCON, like 20 or 30 seconds. > 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. It's been really long time since I read the OTG spec. There may be some diagram showing the required timeouts in the spec if there is one for VBUS. Maybe we need some property to specify vbus-always-on-in-host-mode? Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751529AbdC0RJy (ORCPT ); Mon, 27 Mar 2017 13:09:54 -0400 Received: from muru.com ([72.249.23.125]:42266 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751194AbdC0RJq (ORCPT ); Mon, 27 Mar 2017 13:09:46 -0400 Date: Mon, 27 Mar 2017 09:59:47 -0700 From: Tony Lindgren To: Moreno Bartalucci Cc: Bin Liu , Lars Melin , "linux-omap@vger.kernel.org" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Alessio Igor Bogani Subject: Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Message-ID: <20170327165946.GL10760@atomide.com> 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> <63FD9E13-2B70-485C-80A7-206BEC16905A@tecnorama.it> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <63FD9E13-2B70-485C-80A7-206BEC16905A@tecnorama.it> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Moreno Bartalucci [170327 09:23]: > If I understood your patch, however, if the device (anyone, not just my one) takes longer to switch, VBUS is deasserted anyway. Yeah some of them can take at least 10 seconds even to enumerate. So probably we need to have to have some longer timeout set for OTG_STATE_A_WAIT_BCON, like 20 or 30 seconds. > 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. It's been really long time since I read the OTG spec. There may be some diagram showing the required timeouts in the spec if there is one for VBUS. Maybe we need some property to specify vbus-always-on-in-host-mode? Regards, Tony