From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: [PATCH 0/4] ACPI scan handlers Date: Mon, 28 Jan 2013 13:58:35 +0100 Message-ID: <4311642.nDd2RCVeDc@vostro.rjw.lan> References: <1873429.MS5RQDxTye@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <1873429.MS5RQDxTye@vostro.rjw.lan> Sender: linux-kernel-owner@vger.kernel.org To: ACPI Devel Maling List Cc: Greg Kroah-Hartman , Bjorn Helgaas , Mika Westerberg , Matthew Garrett , Yinghai Lu , Jiang Liu , Toshi Kani , LKML List-Id: linux-acpi@vger.kernel.org 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. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.