Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753531Ab3F2LGe (ORCPT ); Sat, 29 Jun 2013 07:06:34 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:54932 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753148Ab3F2LGc (ORCPT ); Sat, 29 Jun 2013 07:06:32 -0400 From: "Rafael J. Wysocki" To: Yinghai Lu Cc: ACPI Devel Maling List , LKML , Bjorn Helgaas , Jiang Liu , "Alexander E. Patrakov" Subject: Re: [PATCH 1/3] ACPI / dock: Rework the handling of notifications Date: Sat, 29 Jun 2013 13:16:01 +0200 Message-ID: <2193112.vKUrhiifXu@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.10.0-rc5+; KDE/4.9.5; x86_64; ; ) In-Reply-To: References: <1640211.P0jyS5muX2@vostro.rjw.lan> <1771749.8rDXNf8giR@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 Content-Length: 2306 Lines: 51 On Friday, June 28, 2013 04:34:21 PM Yinghai Lu wrote: > On Fri, Jun 28, 2013 at 3:53 PM, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki > > > > The ACPI dock driver uses register_acpi_bus_notifier() which > > installs a notifier triggered globally for all system notifications. > > That first of all is inefficient, because the dock driver is only > > interested in notifications associated with the devices it handles, > > but it has to handle all system notifies for all devices. Moreover, > > it does that even if no docking stations are present in the system > > (CONFIG_ACPI_DOCK set is sufficient for that to happen). Besides, > > that is inconvenient, because it requires the driver to do extra work > > for each notification to find the target dock station object. > > > > For these reasons, rework the dock driver to install a notify > > handler individually for each dock station in the system using > > acpi_install_notify_handler(). This allows the dock station > > object to be passed directly to the notify handler and makes it > > possible to simplify the dock driver quite a bit. It also > > reduces the overhead related to the handling of all system > > notifies when CONFIG_ACPI_DOCK is set. > > original change to use register_acpi_bus_notifier, have two assumption > 1. two dock_station will have same handle. Well, that would mean that dock_add() might be called twice for the same handle and I don't see how that's possible. Moreover, even if that were possible, the loop in acpi_dock_notifier_call() would break after finding the *first* matching handle anyway, so acpi_dock_deferred_cb() wouldn't be called for the second dock station with the same handle, if there were two. > 2. acpi subsystem: non root acpi device only can have one system > notifier installed. No, that limitation is long gone. We removed it when we were working on ACPI wakeup support for runtime PM. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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/