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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 65588C00144 for ; Fri, 29 Jul 2022 17:26:38 +0000 (UTC) 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 A0CBC15F9; Fri, 29 Jul 2022 19:25:46 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz A0CBC15F9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1659115596; bh=vj9Gd3F0ZFA+lxnvVFnGuGBsXg4J6Y0l+pUnAC5iJsg=; h=Date:Subject:To:References:From:In-Reply-To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=ciWw2elolMWblqMf2yk9lP6fg/TuaR2ZWutcy70FTEOKm4ja3pqAP/mO/D/94u7dL 0BSh8+x7BEOY4oqbWTyiIsFm4FGVoYaFDX1Tuw3KasJOxPpbqI6UpwLmyUpMJ0VL9y dnadyUHp5wOS7mdfdCY3A3WZtxdRVDUojN7hoh5w= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 2CC89F8015B; Fri, 29 Jul 2022 19:25:46 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id A4DBCF8049C; Fri, 29 Jul 2022 19:25:45 +0200 (CEST) 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 029D5F8015B for ; Fri, 29 Jul 2022 19:25:39 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 029D5F8015B Authentication-Results: alsa1.perex.cz; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="ig8gS6dx" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1659115543; x=1690651543; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=vj9Gd3F0ZFA+lxnvVFnGuGBsXg4J6Y0l+pUnAC5iJsg=; b=ig8gS6dxEWunignipwLlmHNh9kCyChXG1oYkmLHKlmjtjH6or4HsPtCV 5pWrbXberk9Ct0xEcZwMA1/+4hBlYV0P8xVk8F0vPRgbLm8GnLc964Fqt hA0FQ2Sai+mmuwZ9XNzv5y9nFnu+cDnOxqgDaVsffYOAU8v8oE03BV2Dt WSQGoFyQlPtNDN9NY1lSQ5K7l4GSWJgzPqjPemrwovl7S9SB3lnV/wGhb 0So+cyN4C5Ohqef/4CE17slP2Mt9+XbAg3YFw7qv3jhZU+a1H3nEdIl2B PQs6aCTt4ol8aYnepXKzjOCCebbmLr9nJVs47LGiNApZtnODYqC1eEwsc g==; X-IronPort-AV: E=McAfee;i="6400,9594,10423"; a="268580557" X-IronPort-AV: E=Sophos;i="5.93,201,1654585200"; d="scan'208";a="268580557" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2022 10:25:36 -0700 X-IronPort-AV: E=Sophos;i="5.93,201,1654585200"; d="scan'208";a="605026163" Received: from kaholo-mobl.amr.corp.intel.com (HELO [10.212.97.86]) ([10.212.97.86]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2022 10:25:35 -0700 Message-ID: Date: Fri, 29 Jul 2022 12:25:34 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0 Thunderbird/91.11.0 Subject: Re: [PATCH 2/5] soundwire: sysfs: cleanup the logic for creating the dp0 sysfs attributes Content-Language: en-US To: Greg Kroah-Hartman References: <20220729135041.2285908-1-gregkh@linuxfoundation.org> <20220729135041.2285908-2-gregkh@linuxfoundation.org> <9365e038-2146-98f8-f989-02827f221c34@linux.intel.com> <5caffe2a-f5a6-e312-a564-5fe29c4e2323@linux.intel.com> <701aa1ba-9b25-51eb-8bd7-2389b501d79c@linux.intel.com> From: Pierre-Louis Bossart In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Sanyog Kale , Vinod Koul , Bard Liao , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org 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 7/29/22 12:15, Greg Kroah-Hartman wrote: > On Fri, Jul 29, 2022 at 11:46:32AM -0500, Pierre-Louis Bossart wrote: >> >>>>>>> That should be fine, tools should just be looking for the attributes, >>>>>>> not the existance of a directory, right? >>>>>> >>>>>> The idea what that we would only expose ports that actually exist. >>>>>> That's helpful information anyone with a basic knowledge of the >>>>>> SoundWire specification would understand. >>>>> >>>>> Is "dp0" a port? If so, why isn't it a real device? >>>> >>>> The SoundWire spec defines the concept of 'data port'. The valid ranges >>>> are 1..14, but in all existing devices the number of data ports is way >>>> smaller, typically 2 to 4. Data ports (DPn) are source or sink, and >>>> there's no firm rule that data ports needs to be contiguous. >>>> >>>> DP0 is a 'special case' where the data transport is used for control >>>> information, e.g. programming large set of registers or firmware >>>> download. DP0 is completely optional in hardware, and not handled in >>>> Linux for now. >>>> >>>> DP0 and DPn expose low-level transport registers, which define how the >>>> contents of a FIFO will be written or read from the bus. Think of it as >>>> a generalization of the concept of TDM slots, where instead of having a >>>> fixed slot per frame the slot position/repetition/runlength can be >>>> programmed. >>>> >>>> The data ports could be as simple as 1-bit PDM, or support 8ch PCM >>>> 24-bits. That's the sort of information reported in attributes. >>> >>> Why not make them a real device like we do for USB endpoints? >> >> I don't see what adding another layer of hierarchy would bring. In their >> simplest configuration, there are 6 registers 8-bit exposed. And the >> port registers, when present, are accessed with a plain vanilla offset. > > Who uses these registers? The bus layer. When a 'stream' is created, the 'bit allocation' will define who owns which bitSlots in the frame and the registers will be programmed. The bit allocation may be dynamic or fixed depending on the host. >>> What uses these sysfs files today that would be confused about an empty >>> directory? >> >> That's a good question. I am not aware of any tools making use of those >> attributes. To a large degree, they are helpful only for debug and >> support, all these read-only attributes could be moved to debugfs. That >> could be a way to simplify everyone's life.... > > That would be much nicer, put it all in a single debugfs file and it > would be so simple. > > What attributes could we do that for? All of them really - except maybe the device number which could be used to figure what the device is when looking at power status and other 'standard' sysfs attributes. sdw:3:025d:0714:01 is not really user-friendly, device_number 1 is.