Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932698AbXBKWtV (ORCPT ); Sun, 11 Feb 2007 17:49:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932700AbXBKWtV (ORCPT ); Sun, 11 Feb 2007 17:49:21 -0500 Received: from nigel.suspend2.net ([203.171.70.205]:33391 "EHLO nigel.suspend2.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932698AbXBKWtU (ORCPT ); Sun, 11 Feb 2007 17:49:20 -0500 Subject: Re: [PATCH] Re: NAK new drivers without proper power management? From: Nigel Cunningham Reply-To: nigel@nigel.suspend2.net To: Matthew Garrett Cc: Willy Tarreau , "Rafael J. Wysocki" , Daniel Barkalow , Robert Hancock , linux-kernel , Jeff Garzik , Pavel Machek , pm list In-Reply-To: <20070211121339.GB4204@srcf.ucam.org> References: <200702101130.44471.rjw@sisk.pl> <200702102050.28218.rjw@sisk.pl> <20070211065404.GA943@1wt.eu> <20070211121339.GB4204@srcf.ucam.org> Content-Type: text/plain Date: Mon, 12 Feb 2007 09:49:05 +1100 Message-Id: <1171234145.4493.91.camel@nigel.suspend2.net> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1361 Lines: 31 Hi. On Sun, 2007-02-11 at 12:13 +0000, Matthew Garrett wrote: > On Sun, Feb 11, 2007 at 07:54:04AM +0100, Willy Tarreau wrote: > > > instead of modifying all drivers to explicitly state that they don't support > > it, we should start with a test of the NULL pointer for .suspend which should > > mean exactly the same without modifying the drivers. I find it obvious that > > a driver which does provide a suspend function will not support it. And if > > some drivers (eg /dev/null) can support it anyway, it's better to change > > *those* drivers to explicitly mark them as compatible. > > No, that doesn't work. In the absence of suspend/resume methods, the PCI > layer will implement basic PM itself. In some cases, this works. In > others, it doesn't. There's no way to automatically determine which is > which without modifying the drivers. I think we have it backwards there. Power management support for a driver should always start with the driver itself. If there's a generic routine that can be used for the bus, the driver should explicitly set the routine to the generic routine. Regards, Nigel - 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/