Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753951Ab3GTLM2 (ORCPT ); Sat, 20 Jul 2013 07:12:28 -0400 Received: from mail-db9lp0253.outbound.messaging.microsoft.com ([213.199.154.253]:2544 "EHLO db9outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753688Ab3GTLM1 convert rfc822-to-8bit (ORCPT ); Sat, 20 Jul 2013 07:12:27 -0400 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: -2 X-BigFish: VS-2(zz98dI9371I1432Izz1f42h208ch1ee6h1de0h1fdah2073h1202h1e76h1d1ah1d2ah1fc6hz8dhz1de098h1de097h8275bhz2dh2a8h668h839h8e2h8e3h944hd25hf0ah1220h1288h12a5h12a9h12bdh137ah13b6h1441h1504h1537h153bh15d0h162dh1631h1758h18e1h1946h19b5h1ad9h1b0ah1d0ch1d2eh1d3fh1dfeh1dffh1e1dhbe9i1155h) From: Chen Peter-B29397 To: Rong Wang CC: Greg KH , "balbi@ti.com" , Arnd Bergmann , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Rong.Wang@csr.com" Subject: RE: [PATCH] usb: udc: add gadget state kobject uevent Thread-Topic: [PATCH] usb: udc: add gadget state kobject uevent Thread-Index: AQHOgQ/L6yTmjsCbR0ibTspDf9T00pll9SqAgAC3joCAAC1PgIAB1u+AgAFtlYCAA019sA== Date: Sat, 20 Jul 2013 10:57:13 +0000 Message-ID: References: <20130715165209.GA6000@kroah.com> <20130716063117.GA30320@kroah.com> <20130717023649.GD29679@nchen-desktop> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.192.185.215] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-OriginatorOrg: freescale.com X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2516 Lines: 74 > > On Wed, Jul 17, 2013 at 10:36 AM, Peter Chen > wrote: > > On Mon, Jul 15, 2013 at 11:31:17PM -0700, Greg KH wrote: > >> On Tue, Jul 16, 2013 at 11:49:07AM +0800, Rong Wang wrote: > >> > Hi Greg, > >> > > >> > The USB on our platform can change roles between HOST and GADGET, > but > >> > it is not capable of OTG. > >> > >> That kind of sounds like the definition of OTG :) > >> > >> > When the USB changes between roles the udev will run some scripts > >> > automatically according to the udev rules. > >> > >> What exactly does udev/userspace see when the roles change? > >> > >> And what can trigger the change in roles? > >> > >> > The default role is GADGET, and we bind the g_mass_storage to the > USB > >> > GADGET role. > >> > > >> > We should secure the back end file storage between the device and > the > >> > host PC connecting to our device. > >> > We need to know when the GADGET is really connect to a host PC, then > >> > we can umount the file on the device > >> > and export it to the g_mass_storage. > >> > >> I thought you already get an event for this, otherwise no one would be > >> able to properly deal with this. > >> > >> > The question is since we default GADGET, so the g_mass_storage.ko is > >> > installed early but connecting to a host PC > >> > is randomly, But the udev has no idea when a host PC connects our > device. > >> > > >> > So we consider it's reasonable to let the udev know the GADGET > device state. > >> > Is there any alternative to our question? > >> > >> I thought we already export events for gadget device states, have you > >> looked for them? I can't dig through the code at the moment, but this > >> seems like a pretty common issue... > >> > > > > If I understand correctly, what Rong wants is udev can be notified the > > udc state changes, like connect/disconnect event. Currently, we only > > export it to /sys. > > OK. Thanks for your share. > > And you develop a new utility rather than udev to monitor that file? > And you probably create a work queue in your udc driver to do this work? > Not yet, no one complains it, so I haven't added it. But, it is a useful user interface, Android has implemented similar functions at its gadget driver. Best regards, Peter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/