Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751753Ab3CZRKd (ORCPT ); Tue, 26 Mar 2013 13:10:33 -0400 Received: from cora.hrz.tu-chemnitz.de ([134.109.228.40]:44117 "EHLO cora.hrz.tu-chemnitz.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751245Ab3CZRKc (ORCPT ); Tue, 26 Mar 2013 13:10:32 -0400 Message-ID: <5151D686.9070701@web.de> Date: Tue, 26 Mar 2013 18:10:30 +0100 From: Danny Baumann User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 MIME-Version: 1.0 To: Matthew Garrett CC: David Airlie , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/1] drm/i915: Allow specifying a minimum brightness level for sysfs control. References: <1364298525-4337-1-git-send-email-dannybaumann@web.de> <20130326170203.GA23549@srcf.ucam.org> In-Reply-To: <20130326170203.GA23549@srcf.ucam.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-purgate: clean X-purgate-type: clean X-purgate-ID: 154106::1364317831-000004E7-68D43C5F/0-0/0-0 X-Scan-AV: cora.hrz.tu-chemnitz.de;2013-03-26 18:10:31;625c6725f6a0d3fb489f562c43620cf5 X-Scan-SA: cora.hrz.tu-chemnitz.de;2013-03-26 18:10:31;3f6e9083a0b266867468114d93140f74 X-Spam-Score: -1.0 (-) X-Spam-Report: --- Textanalyse SpamAssassin 3.3.1 (-1.0 Punkte) Fragen an/questions to: Postmaster TU Chemnitz * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider * (dannybaumann[at]web.de) --- Ende Textanalyse Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1611 Lines: 38 Hi, Am 26.03.2013 18:02, schrieb Matthew Garrett: > On Tue, Mar 26, 2013 at 12:48:44PM +0100, Danny Baumann wrote: >> This patch makes the behaviour of the intel_backlight backlight device >> consistent to e.g. acpi_videoX: When writing the value 0, the set brightness >> makes the panel content barely readable instead of turning the backlight off. >> This matches the expectations of user space (e.g. kde-workspace or the Intel >> X11 driver), which expects that it can use intel_backlight as a drop-in >> replacement for acpi_videoX. > > I'm not quite clear what you mean here. The behaviour of "0" isn't well > defined for the ACPI backlight driver - it's perfectly reasonable for it > to turn the backlight off entirely. Anything assuming that "0" is still > visible is broken. Well, the ACPI spec says this (section B.5.2): " The OEM may define the number 0 as "Zero brightness" that can mean to turn off the lighting (e.g. LCD panel backlight) in the device. This may be useful in the case of an output device that can still be viewed using only ambient light, for example, a transflective LCD. " My interpretation of this is that the value 0 is supposed to still be visible. I'm pretty sure I saw a statement that 0 is supposed to mean "barely visible" somewhere, but can't find it at the moment. I'll search for the source of it. Regards, Danny -- 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/