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=-4.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 AEE1CC433E2 for ; Fri, 28 Aug 2020 07:28:56 +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 350A3208CA for ; Fri, 28 Aug 2020 07:28:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="CWEBZYh4"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="JAD8CL0E" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 350A3208CA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 CBF26183D; Fri, 28 Aug 2020 09:28:04 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz CBF26183D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1598599734; bh=ZKgBgkPLZoJc/kStyrmzO8ZmcG3Mtvo7x+SL2dAs6h4=; h=Date:From:To:Subject:References:In-Reply-To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=CWEBZYh48XbRlrOUuHm08QVre+DLb8xmSmjBCgTc6SnsiElmKivu22QqB6oRU37BD dfcT3P8tM/eUt1NCOW8w6A6TxHbjFMm3OHXAgeMG5vRRYqfI38YUA98pxznyKfXjYO jVBHK6rs3nqOtKREY7R3IL6PstTRnzObP9sz6xQ4= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 8CDF1F80264; Fri, 28 Aug 2020 09:28:01 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 339DEF80264; Fri, 28 Aug 2020 09:27:59 +0200 (CEST) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 9595DF80105 for ; Fri, 28 Aug 2020 09:27:48 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 9595DF80105 Authentication-Results: alsa1.perex.cz; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="JAD8CL0E" Received: from localhost (unknown [122.171.38.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3E4A1208CA; Fri, 28 Aug 2020 07:27:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598599667; bh=ZKgBgkPLZoJc/kStyrmzO8ZmcG3Mtvo7x+SL2dAs6h4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JAD8CL0Erh/teDxbTuuqQKHrcaC4IOjBehDT+dOCTzkSzWeRm6aLY/L0GxdYa0VnE umaTSwvQm7Jz3t9C7KjMKDt1NSAEiLqpHxe2pHdHW/GGem0ordiP4IKnZlBnVwoZOC G6rH4GRVGr2R2TSr3mFocrivVjQ7KYGo09mAQc94= Date: Fri, 28 Aug 2020 12:57:42 +0530 From: Vinod Koul To: Pierre-Louis Bossart Subject: Re: [PATCH 05/11] soundwire: bus: update multi-link definition with hw sync details Message-ID: <20200828072742.GL2639@vkoul-mobl> References: <20200818024120.20721-1-yung-chuan.liao@linux.intel.com> <20200818024120.20721-6-yung-chuan.liao@linux.intel.com> <20200826094420.GA2639@vkoul-mobl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Cc: alsa-devel@alsa-project.org, tiwai@suse.de, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, ranjani.sridharan@linux.intel.com, hui.wang@canonical.com, broonie@kernel.org, srinivas.kandagatla@linaro.org, jank@cadence.com, mengdong.lin@intel.com, sanyog.r.kale@intel.com, Bard Liao , rander.wang@linux.intel.com, bard.liao@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 26-08-20, 09:09, Pierre-Louis Bossart wrote: > > > > > + * @hw_sync_min_links: Number of links used by a stream above which > > > + * hardware-based synchronization is required. This value is only > > > + * meaningful if multi_link is set. If set to 1, hardware-based > > > + * synchronization will be used even if a stream only uses a single > > > + * SoundWire segment. > > > > Soundwire spec does not say anything about multi-link so this is left to > > implementer. Assuming that value of 1 would mean hw based sync will > > be used even for single stream does not make sense in generic terms. > > Maybe yes for Intel but may not be true for everyone? > > hw-based sync is required for Intel even for single stream. It's been part > of the recommended programming flows since the beginning but ignored so far. > > That said, this value is set by each master implementation, no one forces > non-Intel users to implement an Intel-specific requirement. > > > We already use m_rt_count in code for this, so the question is why is > > that not sufficient? > > Because as you rightly said above, Intel requires the hw_sync to be used > even for single stream, but we didn't want others to be forced to use the > hw-sync for single stream. the m_rt_count is not sufficient for Intel. > > I think we are in agreement on not forcing everyone to follow what is > required by Intel, and that's precisely why we added this setting. If you > set it to two you would only use hw_sync when two masters are used. Okay, it would be better if we move it to intel driver, but I see it may not be trivial, so lets go with this approach. -- ~Vinod