From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753681Ab3A2Acf (ORCPT ); Mon, 28 Jan 2013 19:32:35 -0500 Received: from hydra.sisk.pl ([212.160.235.94]:58067 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751646Ab3A2Aca (ORCPT ); Mon, 28 Jan 2013 19:32:30 -0500 From: "Rafael J. Wysocki" To: Yinghai Lu Cc: ACPI Devel Maling List , Greg Kroah-Hartman , Bjorn Helgaas , Mika Westerberg , Matthew Garrett , Jiang Liu , Toshi Kani , LKML Subject: Re: [PATCH 0/4] ACPI scan handlers Date: Tue, 29 Jan 2013 01:38:39 +0100 Message-ID: <2339953.KGL8ga1dug@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.8.0-rc5; KDE/4.9.5; x86_64; ; ) In-Reply-To: References: <1873429.MS5RQDxTye@vostro.rjw.lan> <4311642.nDd2RCVeDc@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday, January 28, 2013 01:54:30 PM Yinghai Lu wrote: > On Mon, Jan 28, 2013 at 4:58 AM, Rafael J. Wysocki wrote: > > On Thursday, January 24, 2013 01:26:56 AM Rafael J. Wysocki wrote: > >> Hi All, > >> > >> There is a considerable amount of confusion in the ACPI subsystem about what > >> ACPI drivers are used for. Namely, some of them are used as "normal" device > >> drivers that bind to devices and handle them using ACPI control methods (like > >> the fan or battery drivers), but some of them are just used for handling > >> namespace events, such as the creation or removal of device nodes (I guess it > >> would be fair to call that an abuse of the driver core). These two roles are > >> quite distinct, which is particularly visible from the confusion about the role > >> of the .remove() callback. > >> > >> For the "normal" drivers this callback is simply used to handle situations in > >> which the driver needs to be unbound from the device, because one of them > >> (either the device or the driver) is going away. That operation can't really > >> fail, it just needs to do the necessary cleanup. > >> > >> However, for the namespace events handling "drivers" .remove() means that not > >> only the device node in question, but generally also the whole subtree below it > >> needs to be prepared for removal, which may involve deleting multiple device > >> objects belonging to different bus types and so on and which very well may fail > >> (for example, those devices may be used for such things like swap or they may be > >> memory banks used by the kernel and it may not be safe to remove them at the > >> moment etc.). Moreover, for these things the removal of the "driver" doesn't > >> really make sense, because it has to be there to handle the namespace events it > >> is designed to handle or else things will go remarkably awry in some places. > >> > >> To resolve all that mess I'd like to do the following, which in part is inspired > >> by the recent Toshi Kani's hotplug framework proposal and in part is based on > >> some discussions I had with Bjorn and others (the code references made below are > >> based on the current contens of linux-pm.git/linux-next). > >> > >> 1) Introduce a special data type for "ACPI namespace event handlers" like: > >> > >> struct acpi_scan_handler { > >> const struct acpi_device_id *ids; > >> struct list_head list_node; > >> int (*attach)(struct acpi_device *adev); > >> int (*untie)(struct acpi_device *adev); > >> int (*reclaim)(struct acpi_device *adev); > >> void (*detach)(struct acpi_device *adev); > >> }; > > > > After some reconsideration I think that the "untie" and "reclaim" things won't > > be really useful at this level. This means that I only need ACPI scan handlers > > to do .attach() and .detach() and all of that becomes really simple, so I don't > > see reason to wait with that change. > > > > The following patches introduce ACPI scan handlers and make some use of them. > > > > [1/4] Introduce struct acpi_scan_handler for configuration tasks depending on > > device IDs. > > > > [2/4] Make ACPI PCI root driver use struct acpi_scan_handler. > > > > [3/4] Make ACPI PCI IRQ link driver use struct acpi_scan_handler. > > > > [4/4] Use struct acpi_scan_handler for creating platform devices enumerated via ACPI. > > Good, esp you move away hard code in scan.c for platform devices. > > Test with pci root bus hotplug, and it works well. > > So for all 4, > > Acked-by: Yinghai Lu Thanks for the review! > It will have some merging conflicts change in drivers/acpi/internel.h > in pci/next for pci root bus hotplug support. > But it should be very simple to solve it. Yes, it shouldn't be too difficult to resolve them. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.