From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760146Ab2COKvd (ORCPT ); Thu, 15 Mar 2012 06:51:33 -0400 Received: from toro.web-alm.net ([62.245.132.31]:34385 "EHLO toro.web-alm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755623Ab2COKvb (ORCPT ); Thu, 15 Mar 2012 06:51:31 -0400 Message-ID: <4F61C843.8050307@osadl.org> Date: Thu, 15 Mar 2012 11:45:23 +0100 From: Carsten Emde Organization: Open Source Automation Development Lab (OSADL) User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.24) Gecko/20111108 Fedora/3.1.16-1.fc14 Thunderbird/3.1.16 MIME-Version: 1.0 To: Bastien ROUCARIES CC: David Airlie , Alan Cox , Valdis Kletnieks , Thomas Gleixner , Keith Packard , Paul Menzel , DRI , LKML Subject: Re: [V3 PATCH 1/2] drivers-gpu-drm-allow-to-load-edid-firmware.patch References: <20120315095219.520461363@osadl.org> <20120315095357.087317967@osadl.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Bastien, >> Broken monitors and/or broken graphic boards may send erroneous or no >> EDID data. This also applies to broken KVM devices that are unable to >> correctly forward the EDID data of the connected monitor but invent >> their own fantasy data. >> >> This patch allows to specify an EDID data set to be used instead of >> probing the monitor for it. It contains built-in data sets of frequently >> used screen resolutions. In addition, a particular EDID data set may be >> provided in the /lib/firmware directory and loaded via the firmware >> interface. The name is passed to the kernel as module parameter of the >> drm_kms_helper module either when loaded >> options drm_kms_helper edid_firmware=edid/1280x1024.bin >> or as kernel commandline parameter >> drm_kms_helper.edid_firmware=edid/1280x1024.bin > > Windows allow vendor to override eddid based on 3 bytes manufacturer > and product code. This may solve the situation when a particular monitor lies about the required setting or its EDID data set has an invalid CRC. However, this does not solve the situation when we do not get any useful EDID information, because something is totally broken. This also applies to the KVM situation when the KVM sends EDID data that are totally unrelated to the monitor at the other side of the KVM. > Seems a reasonnable approach to follow. I am not yet convinced. -Carsten.