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 EE9BCC433DB for ; Fri, 22 Jan 2021 16:42:06 +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 45EB523A84 for ; Fri, 22 Jan 2021 16:42:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45EB523A84 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com 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 45BBD1614; Fri, 22 Jan 2021 17:41:08 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 45BBD1614 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1611333718; bh=C/geiDc2zIYRH4HMaZ2jFedLsrrWK3tEBTdTBYvj5uY=; h=Subject:From:To:Date:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=sLmpMiP+KLWmUVI6dI2Iv9y/BGSnU+BySBwzPOt5D4YOM2e7XUjIEArM9C2F6ZGpH 9D4slyB1dCKmIWvWwHGaNkwksbom1fuRGQzMzma/LwKVz71uHWh73jMzPlUuKel/o3 v3UK8l/vRYdF91HkRjTgDEqx0twqTJA8UkKbvn5o= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id B2FB3F80166; Fri, 22 Jan 2021 17:41:07 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id AB9D8F8016E; Fri, 22 Jan 2021 17:41:05 +0100 (CET) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id A94D1F80129 for ; Fri, 22 Jan 2021 17:41:00 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz A94D1F80129 IronPort-SDR: 1cG8OoydoWGlODlbMGcGua6n08EBfJTTd6VGKBVLj3WAd84JPEoCXER/SvvlNlfV9k4wLRjgPx JWd0Hwvgtkyg== X-IronPort-AV: E=McAfee;i="6000,8403,9872"; a="158649861" X-IronPort-AV: E=Sophos;i="5.79,367,1602572400"; d="scan'208";a="158649861" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jan 2021 08:40:56 -0800 IronPort-SDR: 5pxU+mVZNOVnvUXvnUwFOBkhp3hVbWG9a+ZCkzo1fjSzewKswqHZ10G0hsJxuSELuW4rDc2H5h /f72YB8dzWWQ== X-IronPort-AV: E=Sophos;i="5.79,367,1602572400"; d="scan'208";a="400724151" Received: from tflint-mobl.amr.corp.intel.com (HELO ovakana-MOBL1.amr.corp.intel.com) ([10.255.229.172]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jan 2021 08:40:56 -0800 Message-ID: <9888b27b0dc9399861ecbee23d5d4ea0d844718c.camel@linux.intel.com> Subject: Re: Question about hdac_ext_link ref_count management From: Ranjani Sridharan To: Takashi Iwai Date: Fri, 22 Jan 2021 08:40:55 -0800 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.3-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit 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, 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? Thanks, Ranjani