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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58B93C05027 for ; Fri, 20 Jan 2023 19:55:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230092AbjATTzJ (ORCPT ); Fri, 20 Jan 2023 14:55:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229489AbjATTzI (ORCPT ); Fri, 20 Jan 2023 14:55:08 -0500 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7CB466197 for ; Fri, 20 Jan 2023 11:55:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1674244507; x=1705780507; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=BBdBbDkOeQZTC5ebPeDBvlm+1/6DpUsVVDUC9OEfcSM=; b=FMrzHqq0zIz3ul/kf9DWXfKW0bvHAzfJ4UNkm7s3nNll1Mp4+z+ermeL F4ryW98xeIjQ1I/qQ6pb5cv5ytzu9+2RMnJXjSsdwfxNvRTmZjLwxY6kD LYy4RseJFH430oFMyJVmjTSjFgQvgFHGDVwhO0Q9FbA+RHvu1/sQmaVoA L0IvqYcDY2BvGRJ5FM0Ebv+dk1AxvU6fnrnuftIg0m+3wor7azsf5Pdna cKCu4TvlNK8eZjTwovjUJXV07gpB2W9O6s+FEEuDFW6Y8nlU+XyCWM7hU h42VYKOyPDrRo99D0/Qkaf46TvY3wbKDz1qWipZqqvCLsfc86AR0fqIuN g==; X-IronPort-AV: E=McAfee;i="6500,9779,10596"; a="352933741" X-IronPort-AV: E=Sophos;i="5.97,233,1669104000"; d="scan'208";a="352933741" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jan 2023 11:55:07 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10596"; a="768800209" X-IronPort-AV: E=Sophos;i="5.97,233,1669104000"; d="scan'208";a="768800209" Received: from gallegos-mobl1.amr.corp.intel.com (HELO [10.212.24.2]) ([10.212.24.2]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jan 2023 11:55:01 -0800 Message-ID: Date: Fri, 20 Jan 2023 13:55:00 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.4.2 Subject: Re: [PATCH v2 6/8] ASoC: cs42l42: Add Soundwire support To: Richard Fitzgerald , Stefan Binding , Mark Brown Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, patches@opensource.cirrus.com References: <20230118160452.2385494-1-sbinding@opensource.cirrus.com> <20230118160452.2385494-7-sbinding@opensource.cirrus.com> <33130336-b2ce-330e-fdec-166eee977e13@linux.intel.com> <418f6b73-b5ac-8d87-a856-3413ec103f91@opensource.cirrus.com> <6ea1b85f-22e2-8744-9638-6321a5a21acf@linux.intel.com> <32fd1755-0128-8f32-9a88-a92f1647f903@opensource.cirrus.com> Content-Language: en-US From: Pierre-Louis Bossart In-Reply-To: <32fd1755-0128-8f32-9a88-a92f1647f903@opensource.cirrus.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/19/23 09:35, Richard Fitzgerald wrote: > On 19/1/23 14:48, Pierre-Louis Bossart wrote: >> >>>>> +static int cs42l42_sdw_dai_startup(struct snd_pcm_substream >>>>> *substream, >>>>> +                   struct snd_soc_dai *dai) >>>>> +{ >>>>> +    struct cs42l42_private *cs42l42 = >>>>> snd_soc_component_get_drvdata(dai->component); >>>>> + >>>>> +    if (!cs42l42->init_done) >>>>> +        return -ENODEV; >>>> >>>> Can this happen? IIRC the ASoC framework would use >>>> pm_runtime_resume_and_get() before .startup, which would guarantee that >>>> the device is initialized, no? >>>> >>> >>> Yes, this can happen. Because of the way that the SoundWire enumeration >>> was implemented in the core code, it isn't a probe event so we cannot >>> call snd_soc_register_component() on enumeration because -EPROBE_DEFER >>> wouldn't be handled. So the snd_soc_register_component() must be called >>> from probe(). This leaves a limbo situation where we've registered the >>> driver but in fact don't yet have any hardware. ALSA/ASoC doesn't know >>> that we've registered before we are functional so they are happy to >>> go ahead and try to use the soundcard. If for some reason the hardware >>> failed to enumerate we can get here without having enumerated. >> >> Humm, yes, but you've also made the regmap cache-only, so is there >> really a problem? >> > > It's true that normally we go past these stages in cache-only, but that > is because normally (non-Soundwire) we already initialized the hardware > to good state during probe(). > If we just carry on when it hasn't enumerated and we haven't initialized > it yet, who knows what will happen if it enumerates some time later. > > We could just ignore it and see if anyone has a problem but for the sake > of a couple of lines of code I feel like I'd rather check for it. > >> FWIW I don't see a startup callback in any other codec driver. It may be >> wrong but it's also a sign that this isn't a problem we've seen so far >> on existing Intel-based platforms. >> > > It's nicer to do the check in startup() because then the application > open() will fail cleanly. We could delay until prepare - which is the > point we really need the hardware to be accessible - and hope the > hardware enumerated and initialized by that time. But that's not so > nice from the app point of view. Another way to avoid problems is to rely on the codec component .probe to check if the SoundWire device is initialized before registering a card. I just tried with a system where the ACPI info exposes a codec which is not connected, it fails nicely. That avoids the pitfalls of creating a card which isn't functional since all dependencies are not met. [ 64.616530] snd_soc_sof_sdw:mc_probe: sof_sdw sof_sdw: Entry [ 64.616549] snd_soc_sof_sdw:log_quirks: sof_sdw sof_sdw: quirk SOF_SDW_PCH_DMIC enabled [ 64.616559] snd_soc_sof_sdw:sof_card_dai_links_create: sof_sdw sof_sdw: sdw 2, ssp 0, dmic 2, hdmi 0 [ 64.616587] snd_soc_sof_sdw:init_dai_link: sof_sdw sof_sdw: create dai link SDW0-Playback, id 0 [ 64.616600] snd_soc_sof_sdw:init_dai_link: sof_sdw sof_sdw: create dai link SDW0-Capture, id 1 [ 64.616607] snd_soc_sof_sdw:init_dai_link: sof_sdw sof_sdw: create dai link dmic01, id 2 [ 64.616614] snd_soc_sof_sdw:init_dai_link: sof_sdw sof_sdw: create dai link dmic16k, id 3 [ 69.757115] rt5682 sdw:0:025d:5682:00: Initialization not complete, timed out [ 69.757128] rt5682 sdw:0:025d:5682:00: ASoC: error at snd_soc_component_probe on sdw:0:025d:5682:00: -110 [ 69.757224] sof_sdw sof_sdw: ASoC: failed to instantiate card -110 [ 69.757734] sof_sdw sof_sdw: snd_soc_register_card failed -110 see https://elixir.bootlin.com/linux/latest/source/sound/soc/codecs/rt5682.c#L2927 I think this is compatible with the device model and bind/unbind, but it could be improved with the removal of the wait if we had a way to return -EPROBEDEFER, and have a mechanism to force the deferred probe work to be triggered when a device actually shows up. It's a generic problem that the probe cannot always be a synchronous function but may complete 'later'.