From: Bjorn Helgaas Subject: [PATCH v2 0/8] ACPI: make every acpi_device have a HID Date: Mon, 31 Aug 2009 16:46:45 -0600 Message-ID: <20090831224535.12236.61350.stgit@bob.kio> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from g4t0015.houston.hp.com ([15.201.24.18]:46470 "EHLO g4t0015.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750957AbZHaWqi (ORCPT ); Mon, 31 Aug 2009 18:46:38 -0400 Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Len Brown Cc: linux-acpi@vger.kernel.org, Hugh Dickins , Valdis Kletnieks , Lin Ming , Bartlomiej Zolnierkiewicz This series was prompted by an issue we saw recently in the mm tree: http://lkml.org/lkml/2009/7/20/422 Synopsis: Linux/ACPI discovered a video device. The device had no _HID or _CID methods, but based on acpi_is_video_device(), we added a sythetic CID ("LNXVIDEO"), so the device ended up with a CID but no HID. We bound the acpi_video_bus (drivers/acpi/video.c) driver to the device based on the CID. This driver has a .notify() method, so we tried to install a notify handler on the device. This uses strcmp() on the device HID to determine whether it's a fixed hardware device, and this oopsed because this device had no HID. This used to work because the HID was stored in an array that was initialized to zeroes, but a recent change replaced this with a pointer that is NULL until a HID is set. This thread: http://marc.info/?l=linux-acpi&m=124959955813409&w=2 has patches that work around this by basically returning a pointer to an empty string rather than a NULL pointer in this case. However, the HID is a pretty central part of an acpi_device, and I think it complicates the driver model too much to deal with HIDs that might be empty strings. I think it's better for Linux/ACPI to just make sure that *every* acpi_device has at least one ID (either a HID, a CID, or a synthetic ID). The main place this default "device" ID appears is with ACPI devices that just have _ADR methods, e.g., PCI slots. Original posting: http://marc.info/?l=linux-acpi&m=125113191017124&w=2 Changes from initial post to v2: - Applies on acpi-test (on top of "ACPI: cleanups for hotplug", http://marc.info/?l=linux-acpi&m=125175792329288&w=2). - Removed memory leak fix (folded into v2 of series that introduced it). --- Bjorn Helgaas (8): ACPI: fix synthetic HID for \_SB_ ACPI: use acpi_device_hid() when possible ACPI: make sure every acpi_device has an ID ACPI: maintain a single list of _HID and _CID IDs ACPI: remove acpi_device.flags.compatible_ids ACPI: remove acpi_device.flags.hardware_id ACPI: remove acpi_device_uid() and related stuff ACPI: simplify building device HID/CID list drivers/acpi/scan.c | 279 +++++++++++++------------------------------- drivers/pnp/pnpacpi/core.c | 21 +-- include/acpi/acpi_bus.h | 16 +-- 3 files changed, 101 insertions(+), 215 deletions(-) -- Bjorn