Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933329Ab3GPQWO (ORCPT ); Tue, 16 Jul 2013 12:22:14 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:59954 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932412Ab3GPQWM (ORCPT ); Tue, 16 Jul 2013 12:22:12 -0400 Date: Mon, 15 Jul 2013 23:31:17 -0700 From: Greg KH To: Rong Wang Cc: 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 Message-ID: <20130716063117.GA30320@kroah.com> References: <20130715165209.GA6000@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1668 Lines: 46 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... Felipe, any ideas? greg k-h -- 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/