From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 086E23C08F; Tue, 17 Oct 2023 23:23:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="dwiBqsLe" Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1A5C134; Tue, 17 Oct 2023 16:23:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1697585013; x=1729121013; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=xwQ0iV/rBOQYg8kGL3cqHi/fxn3tom61XgY6fDIexWM=; b=dwiBqsLe6z+g5ULiSf7+jnbg8yc92HCSZXMa7pkVZS4kmqGB5cook92D V4dxiAwQTeP0ZfqMSuXOuc2uV8OoPaotnPrLCl9OfvdCWtB72jDOcfS3T zy0X7tnD6SS63jHsgSd1nBvLfB9S2fcPrfJBZA1TLjVEzU3WJqSqm47GI htrZDnr6IexVAGwZDBKmB5IArS17u+g9U9tc52MdqFQD0mkIIUUva5Vl4 a9lB7FFBAtEHF/zADTPqNuQXIel8DNNkcz5S9hstWrLzkKsW6hslz8Eu8 0Qxl4uCpjxOaLwEPoDITfpiwFPj49bwY9ii5uvZcJBTk0t6clE+yC+5YL w==; X-IronPort-AV: E=McAfee;i="6600,9927,10866"; a="384778247" X-IronPort-AV: E=Sophos;i="6.03,233,1694761200"; d="scan'208";a="384778247" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Oct 2023 16:23:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10866"; a="826637527" X-IronPort-AV: E=Sophos;i="6.03,233,1694761200"; d="scan'208";a="826637527" Received: from asprado-mobl2.amr.corp.intel.com (HELO [10.212.55.179]) ([10.212.55.179]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Oct 2023 16:23:31 -0700 Message-ID: Date: Tue, 17 Oct 2023 18:11:57 -0500 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: [PATCH v9 34/34] ASoC: usb: Rediscover USB SND devices on USB port add Content-Language: en-US To: Wesley Cheng , mathias.nyman@intel.com, gregkh@linuxfoundation.org, lgirdwood@gmail.com, broonie@kernel.org, perex@perex.cz, tiwai@suse.com, agross@kernel.org, andersson@kernel.org, konrad.dybcio@linaro.org, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, srinivas.kandagatla@linaro.org, bgoswami@quicinc.com, Thinh.Nguyen@synopsys.com Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org References: <20231017200109.11407-1-quic_wcheng@quicinc.com> <20231017200109.11407-35-quic_wcheng@quicinc.com> From: Pierre-Louis Bossart In-Reply-To: <20231017200109.11407-35-quic_wcheng@quicinc.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-4.3 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On 10/17/23 15:01, Wesley Cheng wrote: > In case the USB backend device has not been initialized/probed, USB SND > device connections can still occur. When the USB backend is eventually > made available, previous USB SND device connections are not communicated to > the USB backend. Call snd_usb_rediscover_devices() to generate the connect > callbacks for all USB SND devices connected. This will allow for the USB > backend to be updated with the current set of devices available. > > The chip array entries are all populated and removed while under the > register_mutex, so going over potential race conditions: > > Thread#1: > q6usb_component_probe() > --> snd_soc_usb_add_port() > --> snd_usb_rediscover_devices() > --> mutex_lock(register_mutex) > > Thread#2 > --> usb_audio_disconnect() > --> mutex_lock(register_mutex) > > So either thread#1 or thread#2 will complete first. If > > Thread#1 completes before thread#2: > SOC USB will notify DPCM backend of the device connection. Shortly > after, once thread#2 runs, we will get a disconnect event for the > connected device. > > Thread#2 completes before thread#1: > Then during snd_usb_rediscover_devices() it won't notify of any > connection for that particular chip index. Looks like you are assuming the regular USB audio stuff is probed first? What if it's not the case? Have you tested with a manual 'blacklist' and "modprobe" sequence long after all the DSP stuff is initialized? It really reminds me of audio+display issues, and the same opens apply IMHO.