From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: 4.5 regression: ACPI hangs when backlight hotkeys are pressed Date: Mon, 18 Jan 2016 23:25:10 +0100 Message-ID: <1591964.NyM72FoSTm@vostro.rjw.lan> References: 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]:48983 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932442AbcARWY3 (ORCPT ); Mon, 18 Jan 2016 17:24:29 -0500 In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Andy Lutomirski Cc: Linux ACPI , Adrien Schildknecht , Hans de Goede , "Rafael J. Wysocki" On Monday, January 18, 2016 12:52:53 PM Andy Lutomirski wrote: > I'm running 4.4 with the pm+acpi-4.5-rc1-1 merged in. After pressing > the backlight hotkeys a couple times, things start to break. Poking > at hung thread stacks, it appears that calls to > acpi_video_handles_brightness_key_presses never return. > > It appears that the culprit is: > > commit aecbd9b1bff6afbe349921b406b99d285b412820 > Author: Adrien Schildknecht > Date: Mon Jan 4 23:22:28 2016 +0100 > > ACPI / video: driver must be registered before checking for keypresses > > Reverting that patch makes my laptop work again. > > I don't know what that patch is trying to do, but it looks highly > questionable to me. Why should an accessor wait for a potential > different driver to register something? I see no guarantee that it > will eve happen. > > This is a Dell XPS 13 9350. Should be fixed in my linux-next branch, can you please try that one? Rafael