From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH 10/11] acpi: Export acpi_bus_type Date: Mon, 18 Jan 2016 23:46:18 +0100 Message-ID: <1530202.t7e2q1JhJ2@vostro.rjw.lan> References: <1452752207-30382-1-git-send-email-ankitprasad.r.sharma@intel.com> <11845387.lHudWAleac@vostro.rjw.lan> <20160118223907.GA9156@wunner.de> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: Received: from v094114.home.net.pl ([79.96.170.134]:48520 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756558AbcARWph (ORCPT ); Mon, 18 Jan 2016 17:45:37 -0500 In-Reply-To: <20160118223907.GA9156@wunner.de> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Lukas Wunner Cc: Ankitprasad Sharma , intel-gfx@lists.freedesktop.org, akash.goel@intel.com, shashidhar.hiremath@intel.com, tvrtko.ursulin@linux.intel.com, Len Brown , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org On Monday, January 18, 2016 11:39:07 PM Lukas Wunner wrote: > Hi, > > On Mon, Jan 18, 2016 at 11:28:27PM +0100, Rafael J. Wysocki wrote: > > On Monday, January 18, 2016 03:57:29 PM Rafael J. Wysocki wrote: > > > On Monday, January 18, 2016 02:31:00 PM Ankitprasad Sharma wrote: > > > > On Fri, 2016-01-15 at 15:51 +0100, Rafael J. Wysocki wrote: > > > > > On Thursday, January 14, 2016 11:46:46 AM ankitprasad.r.sharma@intel.com wrote: > > > > > > From: Ankitprasad Sharma > > > > > > > > > > > > Some modules, like i915.ko, needs to detect when certain ACPI features > > > > > > are active inorder to prevent corruption on contended resources. > > > > > > In particular, use of BIOS RapidStart Technology may corrupt the contents > > > > > > of the reserved graphics memory, due to unalarmed hibernation. In which > > > > > > case i915.ko cannot assume that it (reserved gfx memory) remains > > > > > > unmodified and must recreate teh contents and importantly not use it to > > > > > > store unrecoverable user data. > > > > > > > > > > > > Signed-off-by: Ankitprasad Sharma > > > > > > Cc: "Rafael J. Wysocki" > > > > > > Cc: Len Brown > > > > > > Cc: linux-acpi@vger.kernel.org > > > > > > Cc: linux-kernel@vger.kernel.org > > > > > > --- > > > > > > drivers/acpi/bus.c | 1 + > > > > > > 1 file changed, 1 insertion(+) > > > > > > > > > > > > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c > > > > > > index a212cef..69509c7 100644 > > > > > > --- a/drivers/acpi/bus.c > > > > > > +++ b/drivers/acpi/bus.c > > > > > > @@ -814,6 +814,7 @@ struct bus_type acpi_bus_type = { > > > > > > .remove = acpi_device_remove, > > > > > > .uevent = acpi_device_uevent, > > > > > > }; > > > > > > +EXPORT_SYMBOL_GPL(acpi_bus_type); > > > > > > > > > > > > /* -------------------------------------------------------------------------- > > > > > > Initialization/Cleanup > > > > > > > > > > > > > > > > No. > > > > > > > > > > I see no reason whatsoever for doing this. > > > > > > > > > > Thanks, > > > > > Rafael > > > > Hi Rafael, > > > > > > > > Thanks for the response. > > > > > > > > Can you please help me with, how to detect the presence of a certain > > > > acpi device using its id (for example, INT3392 for Intel RST device)? > > > > > > If you want to check if the device ir present at all, you cen use > > > acpi_device_is_present() introduced recently (although that would need > > > to be exported if you want to use it from a driver). > > > > I meant acpi_dev_present(), sorry about the mistake. > > > > I guess we should rename it to acpi_device_found() or something similar > > to avoid such confusion in the future. > > The name was chosen because the PCI equivalent is called pci_dev_present() > and I assumed that name already stuck in developers' heads, so if they're > looking for an ACPI presence detection function, that's what they'd look > for first. But "present" in ACPI really means something different. There may be ACPI device objects in the namespace for devices that are not *actually* present. Thanks, Rafael