From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750832AbXBKVKy (ORCPT ); Sun, 11 Feb 2007 16:10:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750838AbXBKVKy (ORCPT ); Sun, 11 Feb 2007 16:10:54 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:40374 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750832AbXBKVKx (ORCPT ); Sun, 11 Feb 2007 16:10:53 -0500 Date: Sun, 11 Feb 2007 22:10:38 +0100 From: Pavel Machek To: Willy Tarreau Cc: Matthew Garrett , "Rafael J. Wysocki" , Daniel Barkalow , nigel@nigel.suspend2.net, Robert Hancock , linux-kernel , Jeff Garzik , pm list Subject: Re: [PATCH] Re: NAK new drivers without proper power management? Message-ID: <20070211211038.GD15445@elf.ucw.cz> References: <200702101130.44471.rjw@sisk.pl> <200702102050.28218.rjw@sisk.pl> <20070211065404.GA943@1wt.eu> <20070211121339.GB4204@srcf.ucam.org> <20070211130943.GA1868@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070211130943.GA1868@1wt.eu> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > 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. > > Then change the PCI layer to do the basic PM only for known compatible > drivers, and modify only the known-compatible drivers to mark them > explicitly compatible. IMHO, it generally is a bad idea to require that > any driver explicitly states what it *does not* support. It's the reason > why users encounter problem on new features with old drivers. For instance, > do you know if the old ISA NE2000 driver breaks suspend ? I don't know, > but I would at least expect it not to support it by default. It's best > to announce what *is* supported and consider everything unimplemented > otherwise explicitly stated. Actually, ne2k driver is okay. ne2k cards are notoriously buggy, so it responds with "****, that damn card has just locked up again, lets reset it". Ok, it takes timeout to realize card is "locked up", so it could be improved... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html