From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaroslav Kysela Subject: Re: [RFC] Fix for conflict of HDMI and SPDIF IEC958 controls Date: Mon, 15 Oct 2012 12:21:18 +0200 Message-ID: <507BE39E.5070306@perex.cz> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail1.perex.cz (mail1.perex.cz [77.48.224.245]) by alsa0.perex.cz (Postfix) with ESMTP id 2CF65264EFF for ; Mon, 15 Oct 2012 12:21:19 +0200 (CEST) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: alsa-devel@alsa-project.org Cc: Takashi Iwai List-Id: alsa-devel@alsa-project.org Date 12.10.2012 17:18, Takashi Iwai wrote: > Hi, > > there is a long-standing problem in HD-audio regarding IEC958 > controls. When both an SPDIF and an HDMI are created on the same > card (e.g. one from analog codec and one from graphics chip), the > driver assigns the IEC958 controls just with new indices, 0, 1, 2... > > The problem is that there is no way to connect between this index and > the actual PCM device. Currently, alsa-lib HDA-Intel.conf has a fixed > configuration: > spdif -> IEC958 xxx index=0, PCM dev=1 > hdmi,0 -> IEC958 xxx index=0, PCM dev=3 > hdmi,1 -> IEC958 xxx index=1, PCM dev=7 > hdmi,2 -> IEC958 xxx index=2, PCM dev=8 > hdmi,3 -> IEC958 xxx index=3, PCM dev=9 > > So obviously spdif and the first hdmi conflict. > > Basically this can be fixed by reassigning each IEC958 control with > the same device number corresponding to the PCM device. That is, for > SPDIF, assign a control element with device=1, for HDMI, > device=3,7... > However, this obviously breaks the old configuration unless user > upgrades the alsa-lib configuration. Thus this is no-go. > > Now here is a compromise: the IEC958 control for SPDIF is reassigned > to device=1 *only* when SPDIF and HDMI coexist. Since the > configuration is anyway broken as is now in such a case, it's no big > deal to fix one side in an incompatible way. (The reason why SPDIF > is re-assigned is that I guess majority of user require more HDMI than > SPDIF in such a configuration.) > > In addition, we need a fix in alsa-lib. Also not for breaking the > compatibility with older kernel, we need some fallback check. I did a > quick hack to alsa-lib conf code and added "skip_rest" option to the > hook element, so that only the first matching element is taken. > > Long story short, I cooked up three patches. One patch is for kernel, > to add the workaround above, and the two are for alsa-lib, one clean > up and one to introduce the skip_rest option (and application to > HDA-Intel.conf). > > My plan is to merge this to 3.8 tree, so it's no urgent issue. > But it's of course always good to fix something. What about to introduce more cleaner solution - export this information using TLV to user space, so alsa-lib can enumerate (distinguish) the spdif and hdmi devices properly. Jaroslav -- Jaroslav Kysela Linux Kernel Sound Maintainer ALSA Project; Red Hat, Inc.