From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rene Herman Subject: Re: -mm: pnp-do-not-stop-start-devices-in-suspend-resume-path.patch breaks resuming isapnp cards Date: Wed, 16 Jan 2008 19:16:39 +0100 Message-ID: <478E4A07.1050803@keyaccess.nl> References: <200801092343.48726.linux@rainbow-software.org> <200801141526.57744.bjorn.helgaas@hp.com> <200801161046.05174.bjorn.helgaas@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from smtpq2.groni1.gr.home.nl (smtpq2.groni1.gr.home.nl [213.51.130.201]) by alsa0.perex.cz (Postfix) with ESMTP id A9F5224526 for ; Wed, 16 Jan 2008 19:20:32 +0100 (CET) In-Reply-To: <200801161046.05174.bjorn.helgaas@hp.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Bjorn Helgaas Cc: Andrew Morton , ALSA development , Ondrej Zary , Takashi Iwai , Linux Kernel , "Rafael J. Wysocki" , Pavel Machek , Pierre Ossman , linux-pm@lists.linux-foundation.org List-Id: alsa-devel@alsa-project.org On 16-01-08 18:46, Bjorn Helgaas wrote: > On Tuesday 15 January 2008 12:51:35 am Jaroslav Kysela wrote: >> Ok, something to explain. These flags exists to allow drivers to >> manually configure (override) PnP resources at init time - we know - for >> example in ALSA - that some combinations simply does not work for all >> soundcards. >> >> The DISABLE flags simply tells core PnP layer - driver will handle >> resource allocation itself, don't do anything, just disable hw physically >> and do not change (allocate) any resources. Value 0x03 is valid in this >> semantics. > > It looks like sound drivers use PNP_DRIVER_RES_DISABLE to say "ignore > what PNP tells us about resource usage and we'll just use the compiled- > in or command-line-specified resources". > > The main reason to do that would be to work around BIOS defects or > to work around deficiencies in the Linux PNP infrastructure (e.g., > maybe we erroneously place another device on top of the sound card > or something). > > I'm just suspicious because PNP_DRIVER_RES_DISABLE is only used in > sound drivers. If it's to work around BIOS defects, why wouldn't > other PNP drivers need it sometimes, too? And wouldn't it be better > to use PNP quirks for BIOS workarounds? Yes. The manual resource setting was recently removed from the ALSA drivers and I'd expect this can now go as a package-deal. >> Unfortunately, suspend / resume complicates things a bit, but PnP core can >> handle DO_NOT_CHANGE flag. But it will just mean - _preserve_ resource >> allocation from last suspend state for this device and enable hw >> physically before calling resume() callback. > > When resuming, wouldn't we *always* want to preserve the resource > allocation from the last suspend, regardless of whether > PNP_DRIVER_RES_DO_NOT_CHANGE is specified? Yes. > Linux PNP definitely has issues with suspend/resume, and I suspect > this is one of them. Rene.