From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 39ADE481B0 for ; Wed, 20 Dec 2023 18:26:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="asQr9Z/L" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1703096794; x=1734632794; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=BlE59YgYyj+Kss6Xe1C7XI51igbB0E4yxLToN2uPzH4=; b=asQr9Z/LUEangM8yrlYabvHcakqla3YXDfmb/zQedXwQiOBAau4X60ME sX2bA1L5BrC7T57mRRowpwPRc4F9hwNPoQfxNLFxR26fGYUygXMkq+d// JszIgeBLOEsJRN2Hi/D5M7okvNcVeu+ygQl26WSamR/E5YBiy+aOWYXtZ NlV8+oDlIdg5iuynCqt2b7ouPUgNdNkQzJLNEOj1wlfjGZCyOYmkqZ8lR QCu9LAAWoEi9GfXMfyit5GyJQ/87PUM0JU5ghYcHZCZ/rqMtFmipuKmly gjgOaxcovAHFA8+Chh2SG8YE1If2sLVN1hhYjkkzPayXGF29PEpI08QQs A==; X-IronPort-AV: E=McAfee;i="6600,9927,10930"; a="375344170" X-IronPort-AV: E=Sophos;i="6.04,291,1695711600"; d="scan'208";a="375344170" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Dec 2023 10:26:33 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10930"; a="810689336" X-IronPort-AV: E=Sophos;i="6.04,291,1695711600"; d="scan'208";a="810689336" Received: from amagnus-mobl2.ger.corp.intel.com (HELO [10.249.35.12]) ([10.249.35.12]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Dec 2023 10:26:27 -0800 Message-ID: <546d698c-3e23-4a92-9081-f1bebd6b33ae@linux.intel.com> Date: Wed, 20 Dec 2023 19:26:24 +0100 Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 01/16] Documentation: driver: add SoundWire BRA description Content-Language: en-US To: Charles Keepax Cc: Mark Brown , linux-sound@vger.kernel.org, alsa-devel@alsa-project.org, tiwai@suse.de, vinod.koul@intel.com, Bard liao , Ranjani Sridharan , Peter Ujfalusi , Kai Vehmanen , srinivas.kandagatla@linaro.org, Krzysztof Kozlowski , vijendar.mukunda@amd.com, Richard Fitzgerald , Shuming Fan , Jack Yu , Oder Chiou References: <20231207222944.663893-1-pierre-louis.bossart@linux.intel.com> <20231207222944.663893-2-pierre-louis.bossart@linux.intel.com> <38d0c1c9-d60c-4ddd-b2ee-091d1717a377@sirena.org.uk> <5b8e74ad-460f-4e68-a17b-3131d810f29b@linux.intel.com> <700e564d-7e87-463a-a764-c4713ddf11cd@linux.intel.com> <20231220151631.GD14858@ediswmail.ad.cirrus.com> From: Pierre-Louis Bossart In-Reply-To: <20231220151631.GD14858@ediswmail.ad.cirrus.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/20/23 16:16, Charles Keepax wrote: > On Tue, Dec 19, 2023 at 06:08:15PM +0100, Pierre-Louis Bossart wrote: >> On 12/19/23 17:53, Mark Brown wrote: >>> On Tue, Dec 19, 2023 at 05:50:30PM +0100, Pierre-Louis Bossart wrote: >>>>> grep for regmap_.*async - cs_dsp.c is the upstream example in a driver, >>>>> or there's the rbtree cache sync code which uses a back door to go into >>>>> an async mode. Basically just variants of all the normal regmap I/O >>>>> calls with a _complete() call you can use to wait for everything to >>>>> happen. The implementation is a bit heavyweight since it was written to >>>>> work with fairly slow buses. >>> >>>> I spent a fair amount of time this afternoon trying to understand the >>>> regmap_async parts, and I am not following where in the code there is an >>>> ordering requirement/enforcement between async and sync usages. >>> >>> The only actual async implementation is SPI which processes things in >>> order of submission, the sync API wraps the async API. >>> >>>> Also is this just me spacing out or there is no regmap_raw_read_async()? >>> >>> Right, there was never any need. >> >> ok. I am starting to think that we could have a new type of regmap, say >> "regmap-sdw-bra", where the use of write_raw_async() would rely on the >> send/wait bus primitives, and write_raw() would fallback to the regular >> read/write commands. We'd need a mutual exclusion to prevent parallel >> async/sync access to the same regmap. >> >> In other words, "memory" areas that are used for firmware downloads >> would be moved to a different regmap with async capabilities and no >> caching support. > > I would be a little inclined to say leave adding a regmap for a > follow up series, whether we add it to the existing regmap or add > a new one, or whatever, it should all sit happily on top of the > API being added in this series. Makes it a little more contained > to focus on one area at a time, and leave this series as adding > core support for BRA. But that said, if we really want to I don't > feel mega strongly on this one. Right, I was probably going too far down in the details for a December 20 post. The point I was trying to make it seems there's consensus that regmap with the async parts would be the API used by SoundWire/ASoC codecs, and the regmap implementation would rely on the bus/host send/wait routines. The regmap stuff will need joint work with codec driver folks so it should indeed be done in a second step when the SoundWire bus/host parts are available. Put differently: is there any sustained objection to the proposal of extending regmap with async BRA transfers?