From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.7]) (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 E1DF71A4F20; Mon, 14 Oct 2024 13:06:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.7 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728911204; cv=none; b=QhPIf86oSv/u66UAUBSQb+0AgCOLpwxkPgoaWIZA44zWZqCmCQJ8CK19x37axg4nfBol18aAFPJPzIquN0K9Uk3SWc3pIPDUUcWNnWFJQl43RNdOTkTA4e2rC6UpXhX2nRVEHbCn3fevsGdmZXwegyfi5GjIZ6/yE9+dtkwuKL0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728911204; c=relaxed/simple; bh=PTBOYMEy5sDrtcwT6alRgPl5WDMXK8h4WMrdqBbUtyI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eqPgtn+mQmej73Mgam19roOtaUKsKZP+ykUP/LjjUzKbVilCo23r4zsc/YtmlVasd+rTMk28DxXbDKwScAb67Br3x2hgmLjbA6PbTO4CXJ8x46B9qq6xy+CzG5skLrsbiDv2WUgloDyNcCWmOGzBScpA9gzDTtZyF7wG/N5mIbY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=SahEqF1d; arc=none smtp.client-ip=192.198.163.7 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="SahEqF1d" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1728911203; x=1760447203; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=PTBOYMEy5sDrtcwT6alRgPl5WDMXK8h4WMrdqBbUtyI=; b=SahEqF1dxhBQi2YZ07lUHo55+o6bkqydkvG/rvAu99YqrdH31xR/YiZn yokMsqafjjbKb50aVmO0Ihuchp60SlpE2cyxqkJca9isRPoBSliIeW6vJ BbemQ86VrbPmktJdB+TAC1jufZYTeuROL7LsOmDw3oVUJuPaj1KIRugkI sJKdlcWdSQb9ooJ9TZMO1Fw3jytU5jgptF6H1p7cGBdSyGF4e/2qlSfWq +zwKFfQhZ+KcCnMNbJRX8qTnbZDd4Yl+r7zXh6kW3ppWupVoFENSmUSZi suzFRR2ET0fEXFJPX/FJ7qKfSIZ6zpal3IUlhs6cszZh3WoFGzWPLHQMZ Q==; X-CSE-ConnectionGUID: tK0wPuleRpSBv+uQjJErnQ== X-CSE-MsgGUID: 1bUvLy8nTj++GxlgQ16oNw== X-IronPort-AV: E=McAfee;i="6700,10204,11224"; a="53678612" X-IronPort-AV: E=Sophos;i="6.11,203,1725346800"; d="scan'208";a="53678612" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2024 06:06:42 -0700 X-CSE-ConnectionGUID: E9t8hJZtRi+7bkSsKuDGBg== X-CSE-MsgGUID: mzLeac+ZReall9eN25SgHg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,203,1725346800"; d="scan'208";a="82192851" Received: from mattu-haswell.fi.intel.com (HELO [10.237.72.199]) ([10.237.72.199]) by fmviesa004.fm.intel.com with ESMTP; 14 Oct 2024 06:06:36 -0700 Message-ID: Date: Mon, 14 Oct 2024 16:08:47 +0300 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 5/5] usb: host: enable sideband transfer during system sleep To: Guan-Yu Lin , Thinh.Nguyen@synopsys.com, gregkh@linuxfoundation.org, mathias.nyman@intel.com, stern@rowland.harvard.edu, yajun.deng@linux.dev, sumit.garg@linaro.org, kekrby@gmail.com, oneukum@suse.com, dianders@chromium.org, perex@perex.cz, tiwai@suse.com, niko.mauno@vaisala.com, andreyknvl@gmail.com, christophe.jaillet@wanadoo.fr, tj@kernel.org, stanley_chang@realtek.com, quic_jjohnson@quicinc.com, ricardo@marliere.net Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org, badhri@google.com, albertccwang@google.com, quic_wcheng@quicinc.com, pumahsu@google.com References: <20241014085816.1401364-1-guanyulin@google.com> <20241014085816.1401364-6-guanyulin@google.com> Content-Language: en-US From: Mathias Nyman In-Reply-To: <20241014085816.1401364-6-guanyulin@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14.10.2024 11.50, Guan-Yu Lin wrote: > Sharing a USB controller with another entity via xhci-sideband driver > creates power management complexities. To prevent the USB controller > from being inadvertently deactivated while in use by the other entity, a > usage-count based mechanism is implemented. This allows the system to > manage power effectively, ensuring the controller remains available > whenever needed. I don't think all this is needed to prevent USB controller from being deactivated while sideband is in use. The modified audio class driver that uses sideband is still bound to a usb interface device, and all normal pm reference counting should work. To me it looks like this code is tricking pm framework into believing the usb device and host controller have successfully suspended during system suspend when they in reality are fully up and running. I'm not sure I fully understand the case this series is solving. Thanks Mathias