Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932440Ab3HNQOJ (ORCPT ); Wed, 14 Aug 2013 12:14:09 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:45547 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1758463Ab3HNQOH (ORCPT ); Wed, 14 Aug 2013 12:14:07 -0400 Date: Wed, 14 Aug 2013 12:14:06 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Mark Brown cc: Greg Kroah-Hartman , Rob Herring , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Felipe Balbi , Grant Likely , , , Subject: Re: Non-enumerable devices on USB and other enumerable buses In-Reply-To: <20130814153906.GU6427@sirena.org.uk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1732 Lines: 44 On Wed, 14 Aug 2013, Mark Brown wrote: > On Wed, Aug 14, 2013 at 10:27:26AM -0400, Alan Stern wrote: > > On Wed, 14 Aug 2013, Mark Brown wrote: > > > > I'd expect that we're just looking at hooks around connection and > > > disconnection here here - if we're looking at much more it seems like we > > > must be doing something wrong. > > > Connection and disconnection of what? > > The device on the bus. > > > In the example mentioned earlier, the GPIOs to power an on-board USB > > hub would have to be initialized when the host controller was started. > > You wouldn't want to wait for the on-board hub to be detected, because > > without those GPIOs set properly, it never would be discovered on the > > USB bus. Right? > > Yes, so you'd want callbacks when the device actually appears and > disappears. No, no -- this is exactly the point I was trying to make. The on-board hub _won't_ appear on the USB bus until the GPIOs are set. Therefore the callback to set the GPIOs needs to be at a different place, not when the device appears. > > Perhaps the platform-level code would need to hook into the places > > where the discoverable bus is registered and unregistered. > > We'd need some way to get information to the drivers still, and to > handle drivers that want to stop and start things. Um... What exactly does this mean? It's so generic, it could apply to anything under drivers/. After all, what driver doesn't want to stop and start things? Alan Stern -- 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/