Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756401AbYCJW0L (ORCPT ); Mon, 10 Mar 2008 18:26:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751732AbYCJWZ5 (ORCPT ); Mon, 10 Mar 2008 18:25:57 -0400 Received: from outbound-sin.frontbridge.com ([207.46.51.80]:45718 "EHLO outbound2-sin-R.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751167AbYCJWZ4 (ORCPT ); Mon, 10 Mar 2008 18:25:56 -0400 X-BigFish: VP X-MS-Exchange-Organization-Antispam-Report: OrigIP: 139.95.251.11;Service: EHS X-WSS-ID: 0JXJCVE-03-DB3-01 Date: Mon, 10 Mar 2008 16:24:07 -0600 From: Jordan Crouse To: Andres Salomon Cc: Andrew Morton , adaplas@gmail.com, linux-kernel@vger.kernel.org, linux-fbdev-devel@lists.sourceforge.net, info-linux@geode.amd.com, rjw@sisk.pl, samuel.thibault@ens-lyon.org Subject: Re: PM/FB/gxfb: add config option that allows disabling of VT switch during suspend Message-ID: <20080310222407.GD589@cosmic.amd.com> References: <20080308204927.73afa56c@ephemeral> <20080310141939.ce1169c0.akpm@linux-foundation.org> <20080310174424.29621e62@ephemeral> <20080310145118.adb0cf1e.akpm@linux-foundation.org> <20080310181446.2fb85eea@ephemeral> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080310181446.2fb85eea@ephemeral> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) X-OriginalArrivalTime: 10 Mar 2008 22:23:09.0404 (UTC) FILETIME=[51FEA9C0:01C882FD] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2536 Lines: 74 On 10/03/08 18:14 -0400, Andres Salomon wrote: > On Mon, 10 Mar 2008 14:51:18 -0700 > Andrew Morton wrote: > > > On Mon, 10 Mar 2008 17:44:24 -0400 > > Andres Salomon wrote: > > > > > On Mon, 10 Mar 2008 14:19:39 -0700 > > > Andrew Morton wrote: > > > > > > > > > > > It would be far preferable to do this via a kernel boot parameter rather > > > > than via a kernel rebuild. > > > > > > > > > > Well, it shouldn't be supported at _all_ unless the framebuffer driver > > > supports it; you're asking for it to be converted to something like the > > > following? > > > > > > > > > > > > #ifdef CONFIG_FBDEV_SUPPORTS_NOSWITCH > > > static int no_vt_switch; > > > #endif > > > > > > int pm_prepare_console(void) > > > { > > > #ifdef CONFIG_FBDEV_SUPPORTS_NOSWITCH > > > if (no_vt_switch) > > > return 0; > > > #endif > > > ... > > > } > > > > > > #ifdef CONFIG_FBDEV_SUPPORTS_NOSWITCH > > > module_param(no_vt_switch, int, 0); > > > MODULE_PARM_DESC(no_vt_switch, "..."); > > > #endif > > > > > > > > > If so, that means extra #ifdef's sprinkled throughout the code. Note > > > that most framebuffer drivers won't be supporting this, and those that > > > do will almost certainly always want vt switching turned off.. > > > > > > > I don't think you need any ifdefs or config options at all, do you? Just > > add a new module parameter to this driver and some little interface into > > the PM core which allows the driver to set no_vt_switch? > > > > That's a possibility, but doesn't adding hooks into PM core for two > drivers (lxfb and gxfb) seems like overkill? I also don't really see > anyone needing to switch back and forth between VT_SWITCH and > NO_VT_SWITCH other than to work around possible bugs in the register > save/restore code.. I like Andrew's idea. I wager This won't be Geode specific for long. Either other drivers will get the hint and add real save/restore code or the GPU subystem code being worked on by the X folks will come along and make the VT switch obsolete for everybody. Either way, I see hooks in the PM core as generic love that everybody can benefit from. Jordan -- Jordan Crouse Systems Software Development Engineer Advanced Micro Devices, Inc. -- 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/