From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 892614772A6; Wed, 29 Jul 2026 11:42:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785325331; cv=none; b=aAq1U+CGZYOytBaDrPAL0N+35FsV9kCBAIrKqCIwHcwpFUwKCZ4ayfrK8FtUgJYiP5F/tfml3G2IH8oQ36vvtIC2maYA+MyYJcbVU9CHJEtB2uKwEt1p4jtk4ztjy86HlvVbkJIkpCEdF94gfL/ga/+tWBxGT0iA/zkYV/Yi3HI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785325331; c=relaxed/simple; bh=6hB/q9Y2sR4PUKGaVsrJU6rbtN/onGHwx02BgLrihnQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TWhnA2ujgBLrr0QjqSkbBs6rMQ3NtZDrCEzGr2h+23celD2KUm0NETrxMSfRYDYbj1FHFd1ynqJjdt2RtoTkM+YscGBzTVK4Ps6tQMnnpDmAI2RyjcZfYVCveuE9ua4vfmZBuOYJI6yiJCtv6IfYaZkjtbTnrFakyvmMNEbz+r0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aVQnaNiA; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aVQnaNiA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B4C41F000E9; Wed, 29 Jul 2026 11:41:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785325330; bh=xHg0SOLDtQCWaGstHBgfK3i8N8/cHf6NYyxxP1x1d2Q=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=aVQnaNiA+3xTNhvqg1R9d44GvEIpmKLq8jtxhpuqfLYx52IVb5FkCbTjCKUJMHhPU P5qfocEoGpkP1F1vWjM+NgNIVsI82jiE8hExlByYuT0bkjYwbB/nhqVLpmgXrzYehV qw8oJs/I8ezM70eCH5yWCOBWMH2EXQ4gIACUwusaPBRydiX0a3d+oBIl18V38eGpaM 0g1OgbNuwSPz0hzLIJmRbYZ+++ek25xF/FcsZaShYUnrclJhqtvNn+m9FeUNd7DfUg IpPTnuEfsNNN+YjIEuGQn+A73U8MRMOprwftsUqXasBpnf7fp14y2IXXkWfwbM1nbR O4Iu+0vH8Mffw== Message-ID: Date: Wed, 29 Jul 2026 13:41:57 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/8] ASoC: SDCA: enable on DT platforms and add Qualcomm WCD9378 (Tambora) codec To: Charles Keepax , Srinivas Kandagatla Cc: Mark Brown , Liam Girdwood , Jaroslav Kysela , Takashi Iwai , Maciej Strozek , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Srinivas Kandagatla , Bard Liao , Pierre-Louis Bossart , Richard Fitzgerald , Jorijn van der Graaf , linux-sound@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, patches@opensource.cirrus.com, linux-kernel@vger.kernel.org References: <20260722234221.884765-1-srinivas.kandagatla@oss.qualcomm.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 23/07/2026 12:17, Charles Keepax wrote: > On Thu, Jul 23, 2026 at 12:42:10AM +0100, Srinivas Kandagatla wrote: >> At Linux Plumbers 2025 in the Devicetree MC I raised the "SDCA and the >> classic ACPI-DT problem" [1]: MIPI SDCA is built around ACPI/DisCo >> firmware descriptors, and the in-tree ASoC SDCA framework >> (sound/soc/sdca/) enumerates functions, entities, controls and PDEs by >> walking those tables. On ARM64 DT platforms there is no DisCo, so the >> framework is unreachable and sdca codecs will not be able to use the >> generic sdca drivers and duplicating. >> >> The direction from that discussion was to let DT platforms reuse the >> same class/function auxiliary driver plumbing and have codec drivers >> supply the small amount of static function/entity metadata that DisCo >> would otherwise carry, plus hooks for device-specific bring-up. This >> series is a first cut at that, with the Qualcomm WCD9378 ("Tambora") >> SDCA codec on the Glymur CRD as the first consumer. Static table that in >> part of this codec is generated from acpi tables. > > Fascinating, a shame I missed the discussion. Main question > I have is what was the reasoning behind using static tables > rather than just putting the data in device tree? All the core > code uses the generic firmware parsing function so should be > perfectly capable of parsing the data out of device tree. The > only bit that is missing is really the sdca_lookup_functions > bit you ifdef out, but updating that to also support DT should > be pretty simple. > > Looking through your presentation (thanks for linking that), > am I to guess this was mostly a device tree people didn't like > the stuff SDCA contains problem? I do see that some of the SDCA > stuff isn't an exact match for how Linux has traditionally liked > to handle DT but also really not sure I see any benefit to DT > and ACPI support being different. We do not describe in DT properties which are implied/deducible from the compatible, because it is redundant and we do not like redundancy. The device is WCD9378 as defined by compatible, thus all or most of SDCA properties do not belong to DT. Best regards, Krzysztof