Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753303Ab3HDBSN (ORCPT ); Sat, 3 Aug 2013 21:18:13 -0400 Received: from mail-pd0-f181.google.com ([209.85.192.181]:49961 "EHLO mail-pd0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752174Ab3HDBSM (ORCPT ); Sat, 3 Aug 2013 21:18:12 -0400 Message-ID: <51FDABFD.3070601@gmail.com> Date: Sun, 04 Aug 2013 09:18:53 +0800 From: Aaron Lu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: "Rafael J. Wysocki" CC: Felipe Contreras , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, Len Brown , Zhang Rui Subject: Re: [PATCH] acpi: video: improve quirk check References: <1375472229-1563-1-git-send-email-felipe.contreras@gmail.com> <3682340.ddGL4l7l22@vostro.rjw.lan> <51FCBBCC.6060307@gmail.com> <13505759.IqzsRNCUnN@vostro.rjw.lan> In-Reply-To: <13505759.IqzsRNCUnN@vostro.rjw.lan> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2136 Lines: 56 On 08/03/2013 07:34 PM, Rafael J. Wysocki wrote: > On Saturday, August 03, 2013 04:14:04 PM Aaron Lu wrote: >> On 08/03/2013 07:47 AM, 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? >> >> Yes, the patch is correct, but I still prefer my own version :-) >> https://github.com/aaronlu/linux/commit/0a3d2c5b59caf80ae5bb1ca1fda0f7bf448b38c9 >> >> In case you want to take mine and mine needs refresh, please let me know >> and I can do the re-base, thanks. > > Well, I prefer simpler, unless there's a good reason to use more complicated. > > Why exactly do you think your version is better? As explained here: https://lkml.org/lkml/2013/8/2/81 https://lkml.org/lkml/2013/8/2/112 And for the demo broken _BQC, mine patch will disable _BQC while still make the backlight work, and this patch here is testing the max brightness level and may fail. -Aaron -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/