From mboxrd@z Thu Jan 1 00:00:00 1970 From: Felipe Contreras Subject: Re: [PATCH] acpi: video: improve quirk check Date: Fri, 2 Aug 2013 20:04:52 -0500 Message-ID: References: <1375472229-1563-1-git-send-email-felipe.contreras@gmail.com> <3682340.ddGL4l7l22@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-la0-f45.google.com ([209.85.215.45]:49962 "EHLO mail-la0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753071Ab3HCBEy (ORCPT ); Fri, 2 Aug 2013 21:04:54 -0400 In-Reply-To: <3682340.ddGL4l7l22@vostro.rjw.lan> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" Cc: Aaron Lu , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, Len Brown , Zhang Rui On Fri, Aug 2, 2013 at 6:47 PM, Rafael J. Wysocki wrote: > On Friday, August 02, 2013 02:37:09 PM Felipe Contreras wrote: >> If the _BCL package is descending, the first level (br->levels[2]) will >> be 0, and if the number of levels matches the number of steps, we might >> confuse a returned level to mean the index. >> >> For example: >> >> current_level = max_level = 100 >> test_level = 0 >> returned level = 100 >> >> In this case 100 means the level, not the index, and _BCM failed. But if >> the _BCL package is descending, the index of level 0 is also 100, so we >> assume _BQC is indexed, when it's not. >> >> This causes all _BQC calls to return bogus values causing weird behavior >> from the user's perspective. For example: xbacklight -set 10; xbacklight >> -set 20; would flash to 90% and then slowly down to the desired level >> (20). >> >> The solution is simple; test anything other than the first level (e.g. >> 1). >> >> Signed-off-by: Felipe Contreras > > Looks reasonable. > > Aaron, what do you think? Aaron has a similar patch does many more checks. I think we should add more checks, but I think those should go into a separate patch. This patch alone fixes a real problem, which is rather urgent to fix, and I did it this way so it's trivial to review and merge. -- Felipe Contreras