From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE994C433E0 for ; Fri, 22 Jan 2021 16:51:24 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 18EB723A9A for ; Fri, 22 Jan 2021 16:51:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 18EB723A9A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 9F01816B9; Fri, 22 Jan 2021 17:50:32 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 9F01816B9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1611334282; bh=H8pNiSJ7MihiHmB5EoVcknuz47Ydm8VVyyQ3fGfQmgQ=; h=Date:From:To:Subject:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=dSv/HWaObu+8zsnx2BLvULAoD3GXX0UUpviQOfEiRrO7WIT1VX03qyLfDgst6QE/l QLu7Ka7w5jVEdbfALTyXG0b5Yba/u/eUm4rZDPp3Myp/wUqERFAONYk/pELRFBGEMO erjU1TKet3wwMNAGlLoviGQVXSglZ9ErqJ9s9JyI= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 0B801F80166; Fri, 22 Jan 2021 17:50:32 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 67AC1F8016E; Fri, 22 Jan 2021 17:50:30 +0100 (CET) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id B820AF8015B for ; Fri, 22 Jan 2021 17:50:26 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz B820AF8015B X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id BE5AAB7D9; Fri, 22 Jan 2021 16:50:25 +0000 (UTC) Date: Fri, 22 Jan 2021 17:50:25 +0100 Message-ID: From: Takashi Iwai To: Ranjani Sridharan Subject: Re: Question about hdac_ext_link ref_count management In-Reply-To: <9888b27b0dc9399861ecbee23d5d4ea0d844718c.camel@linux.intel.com> References: <9888b27b0dc9399861ecbee23d5d4ea0d844718c.camel@linux.intel.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Cc: alsa-devel@alsa-project.org, kai.vehmanen@linux.intel.com X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Fri, 22 Jan 2021 17:40:55 +0100, Ranjani Sridharan wrote: > > On Fri, 2021-01-22 at 15:12 +0100, Takashi Iwai wrote: > > On Fri, 22 Jan 2021 00:23:53 +0100, > > Ranjani Sridharan wrote: > > > Hi Takashi, > > > > > > While exploring some power optimizations on Intel platforms, I > > > noticed > > > that the hdac_ext_link ref_count is incremented during codec probe > > > in hdac_hda_codec_probe() and the ref_count is held until the codec > > > device is removed. > > > > > > I was wondering if it would be possible to call the get/put for the > > > hdac_ext_link in the codec runtime suspend/resume callbacks so that > > > the > > > link is powered up only when the link is in use. Are there any > > > downsides to doing this? > > > > Wouldn't the snd_hdac_ext_bus_link_power_up() / down() calls do the > > runtime PM stuff? Maybe we need to revisit those link power > > management. The ext stuff isn't well m > > and, I'm afraid. > Thanks, Takashi. > It looks like snd_hdac_ext_bus_link_power_up/down() are only called > during snd_hdac_ext_bus_link_get/put(). Actually, in my observation > disabling the CORB/RIRB buffer DMAs is what saves us power and this is > done only if snd_hdac_ext_bus_link_put() is called on all links. > > > > > The get() and put() are obviously for fully enabling and disabling > > the > > device, hence it's not suitable for the runtime PM suspend/resume. > > The power_up() / down() should be adjusted to fit with the runtime PM > > call, if any. > > The only additional thing that snd_hdac_ext_bus_link_get/put() does on > top of snd_hdac_ext_bus_link_power_up/down() is to stop the CORB/RIRB > DMA when all the link ref_counts are 0. Do you think it is not > advisable to stop the CORB/RIRB DMA during runtime PM? Why do you need to stop CORB/RIRB? For stopping the CORB/RIRB DMA, you need to disable the IRQ and other stuff at first, in anyway. Takashi