Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760090Ab3HNQau (ORCPT ); Wed, 14 Aug 2013 12:30:50 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:50329 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760002Ab3HNQas (ORCPT ); Wed, 14 Aug 2013 12:30:48 -0400 Message-ID: <520BB0B4.4090400@wwwdotorg.org> Date: Wed, 14 Aug 2013 10:30:44 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: Alan Stern CC: Mark Brown , Greg Kroah-Hartman , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Felipe Balbi , Grant Likely , devicetree@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Non-enumerable devices on USB and other enumerable buses References: In-Reply-To: X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1531 Lines: 36 On 08/14/2013 10:14 AM, Alan Stern wrote: > 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. The device Mark was talking about is the controller end of the bus (EHCI controller, or hub's downstream port) not the device end of the bus (any USB device's upstream port). -- 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/