From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Hopf Subject: Re: [PATCH] ACPI / PM: Traverse video_device_list for backlight restoration Date: Tue, 3 Aug 2010 12:11:57 +0200 Message-ID: <20100803101157.GA29721@suse.de> References: <20100803100505.GA26948@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from cantor2.suse.de ([195.135.220.15]:36813 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755758Ab0HCKL7 (ORCPT ); Tue, 3 Aug 2010 06:11:59 -0400 Content-Disposition: inline In-Reply-To: <20100803100505.GA26948@suse.de> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Zhang Rui , Len Brown , Matthew Garrett , Andrew Morton , Julia Lawall , Oliver Cc: linux-acpi@vger.kernel.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org A bit of background about this patch: acpi_video_bus_get_devices() explicitly calls acpi_video_device_enumerate() before acpi_video_bus_get_one_device(), which does acpi_video_device_bind(). In _enumerate(), active_list[] is created, with .bind_info explicitly set to NULL, while the related .bind_info entry in video_device_list is set to the acpi_video_device ptr in _bind(). The .bind_info is later used in acpi_video_resume() to re-set the backlight - but it's only evaluated on the active_list[], on which all .bind_info are NULL by construction. This results in backlight not being restored, if the BIOS doesn't do this by itself already. The patch resolves this by replacing the active_list[] traversal by a video_device_list traversal, but due to the nature of the issue I'm unsure whether the original issue isn't of more principal quality. I don't understand why the list is (partially) transformed into an array in the first place, especially as both the array *and* the list are used in the code... Thanks Matthias -- Matthias Hopf __ __ __ Maxfeldstr. 5 / 90409 Nuernberg (_ | | (_ |__ mat@mshopf.de Phone +49-911-74053-715 __) |_| __) |__ R & D www.mshopf.de