Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758843Ab2HHQ1c (ORCPT ); Wed, 8 Aug 2012 12:27:32 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:43961 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758813Ab2HHQ13 (ORCPT ); Wed, 8 Aug 2012 12:27:29 -0400 MIME-Version: 1.0 In-Reply-To: <50228968.3070904@gmail.com> References: <1344082443-4608-1-git-send-email-jiang.liu@huawei.com> <1344382695.3010.770.camel@misato.fc.hp.com> <50228968.3070904@gmail.com> From: Bjorn Helgaas Date: Wed, 8 Aug 2012 09:27:07 -0700 Message-ID: Subject: Re: [RFC PATCH v2 00/16] ACPI based system device hotplug framework To: Jiang Liu Cc: Toshi Kani , Jiang Liu , Yinghai Lu , Yasuaki Ishimatsu , Kenji Kaneshige , Wen Congyang , Tang Chen , Taku Izumi , Tony Luck , Huang Ying , Bob Moore , Len Brown , "Srivatsa S. Bhat" , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1807 Lines: 32 On Wed, Aug 8, 2012 at 8:44 AM, Jiang Liu wrote: > On 08/08/2012 07:38 AM, Toshi Kani wrote: >> It is nice to see redundant ACPI namespace walks removed from the ACPI >> drivers. But why do you need to add a new enumerator to create the >> acpihp_slot tree, in addition to the current acpi_device tree? I'd >> prefer hotplug features to be generally integrated into the current ACPI >> core code and data structures, instead of adding a new layer on top of >> it. > The idea comes from PCI hotplug framework, which has an concepts of PCI > hotplug slot and PCI device. For system device hotplug, we could follow > the same model as PCI by abstracting control points as slots. By introducing > of hotplug slot, we could: > > 1) Report all hotplug slots and slot's capabilities to user, no matter whether > there are devices connecting to a slot. If we integrate hotplug functionality > into current ACPI device tree, the slot (or device) is only visible when the > connected devices are enabled. In PCI, the idea of a slot is a pretty explicit -- you can look at the capabilities of a bridge device and see whether it supports hot-add of a device below it. Is it the same way in ACPI? My impression is that it is not: there will be a parent ACPI device under which a new device can be added, but you might not be able to tell by looking at the parent device that hot-add is possible. I thought the platform could just give us a Notify event on the parent, asking us to rescan the namespace below it and potentially discover new devices. -- 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/