From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH 6/6] PM/FB/gxfb: add config option that allows disabling of VT switch during suspend Date: Mon, 10 Mar 2008 15:28:28 -0700 Message-ID: <20080310152828.8f102f52.akpm@linux-foundation.org> References: <20080308204927.73afa56c@ephemeral> <20080310141939.ce1169c0.akpm@linux-foundation.org> <20080310174424.29621e62@ephemeral> <20080310145118.adb0cf1e.akpm@linux-foundation.org> <20080310181446.2fb85eea@ephemeral> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1JYqVP-0001B5-QU for linux-fbdev-devel@lists.sourceforge.net; Mon, 10 Mar 2008 15:30:03 -0700 Received: from smtp1.linux-foundation.org ([140.211.169.13]) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1JYqVO-0007T5-GU for linux-fbdev-devel@lists.sourceforge.net; Mon, 10 Mar 2008 15:30:03 -0700 In-Reply-To: <20080310181446.2fb85eea@ephemeral> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-fbdev-devel-bounces@lists.sourceforge.net Errors-To: linux-fbdev-devel-bounces@lists.sourceforge.net To: Andres Salomon Cc: linux-fbdev-devel@lists.sourceforge.net, adaplas@gmail.com, linux-kernel@vger.kernel.org, info-linux@geode.amd.com, rjw@sisk.pl, jordan.crouse@amd.com, samuel.thibault@ens-lyon.org On Mon, 10 Mar 2008 18:14:46 -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? It's just a few bytes of code? > 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.. Making driver behaviour depend upon compile-time settings is really to be avoided. A distributor has to choose one setting or the other, and a) that means that some people will get the wrong setting and b) there's a decent chance that the distributor will get it wrong. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/