From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sid Boyce Subject: Multimonitor support on ARM Date: Wed, 04 Jun 2014 12:57:33 +0100 Message-ID: <538F09AD.6030108@blueyonder.co.uk> Reply-To: sboyce@blueyonder.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from know-smtprelay-omc-5.server.virginmedia.net ([80.0.253.69]:47965 "EHLO know-smtprelay-omc-5.server.virginmedia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752441AbaFDMDS (ORCPT ); Wed, 4 Jun 2014 08:03:18 -0400 Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "linux-omap@vger.kernel.org" I don't know if this is fixable or even considered for ARM. I have a Lilliput 7" USB LCD that works fine on a Beaglebone White with the udlfb kernel module. I started looking at the issue after a guy asked me if it also works on the ODROID. For Software Defined Radio (SDR) which is of prime interest it would be nice to have a portable/mobile SDR with a small keyboard/7" USB LCD or touchscreen, all as a compact unit. Digging further. The Beaglebone does not have a GPU so that's probably why it works there and on x86_64 as it's dependent on x86. The ODROID has a Mali400 GPU. In /etc/modprobe.d/blacklist-framebuffer.conf ##blacklist udlfb blacklist udl The Lilliput came up on the ODROID with a green screen background but no display. root@odroid:~# grep -i arbiter /var/log/Xorg.0.log.old [ 200.165] (WW) VGA arbiter: cannot open kernel arbiter, no multi-card support In kernels on x86_64 there is an option that is not available for ARM. # CONFIG_VGA_ARB is not set The files are present in the kernel but no config option, configuring it by hand and doing "make oldconfig" removes it as it depends on PCI and x86. root@odroid:/b1/linux-3.8.13.23# ls drivers/gpu/vga built-in.o Kconfig Makefile modules.builtin modules.order vgaarb.c vga_switcheroo.c drivers/gpu/vga/Kconfig =============== config VGA_ARB bool "VGA Arbitration" if EXPERT default y depends on (PCI && !S390) help Some "legacy" VGA devices implemented on PCI typically have the same hard-decoded addresses as they did on ISA. When multiple PCI devices are accessed at same time they need some kind of coordination. Please see Documentation/vgaarbiter.txt for more details. Select this to enable VGA arbiter. config VGA_ARB_MAX_GPUS int "Maximum number of GPUs" default 16 depends on VGA_ARB help Reserves space in the kernel to maintain resource locking for multiple GPUS. The overhead for each GPU is very small. config VGA_SWITCHEROO bool "Laptop Hybrid Graphics - GPU switching support" depends on X86 depends on ACPI select VGA_ARB help Many laptops released in 2008/9/10 have two GPUs with a multiplexer to switch between them. This adds support for dynamic switching when X isn't running and delayed switching until the next logoff. This feature is called hybrid graphics, ATI PowerXpress, and Nvidia HybridPower. Regards Sid. On 03/06/14 14:53, Michael Durkin wrote: > and its working on the Odrod? > > On Tue, Jun 3, 2014 at 4:49 AM, Sid Boyce wrote: >> A number of years actually. -- Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support Senior Staff Specialist, Cricket Coach Microsoft Windows Free Zone - Linux used for all Computing Tasks