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 15680C10DCE for ; Thu, 7 Dec 2023 10:27:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231923AbjLGK1M (ORCPT ); Thu, 7 Dec 2023 05:27:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38530 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230234AbjLGK1L (ORCPT ); Thu, 7 Dec 2023 05:27:11 -0500 Received: from mx0b-0031df01.pphosted.com (mx0b-0031df01.pphosted.com [205.220.180.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69E54128; Thu, 7 Dec 2023 02:27:17 -0800 (PST) Received: from pps.filterd (m0279870.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3B79XKj2011699; Thu, 7 Dec 2023 10:26:57 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=qcppdkim1; bh=RuICPUQra4CeTJPKT9XkYJ/b9ZFT1AHX1daHHwFg8KY=; b=me+C4CHyioh3xO7xx7c9nqXvkzL+5bEER0WA0y7rPCG+yEunUh1LVCeEp1xBYpwRgbz8 ooeApKYNdo50OET8cjorU2xc+OY1fwBWydHQ0a1ZrYxwO+nPxGgXJl5Y7dKhuB+faejB dbtcjmJxjoBLOSlsBNBUUcID1qO8LiqWSbGBgjJZEeLoBbM6e5GgEHTt7awQQOR80/GW 1KxjbvHfaiVTg9iRCMtHeryEeedVSeuqGFk90n5CwxHXzpnXXjBs+lTbEOnvublRJgnk 7uMObRwT2HW32Lui89pkuBqWwQPo+l5kByVNcdQklurGjOF3jU9NlkMI7WLCU5bZyfRG Rw== Received: from nalasppmta03.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3uu928geh0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 07 Dec 2023 10:26:57 +0000 Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA03.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 3B7AQton012717 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 7 Dec 2023 10:26:55 GMT Received: from [10.218.45.181] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Thu, 7 Dec 2023 02:26:48 -0800 Message-ID: <286b6f8a-c634-19ed-cf53-276cfe05d03f@quicinc.com> Date: Thu, 7 Dec 2023 15:56:43 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.3.2 Subject: Re: [PATCH V2 1/3] ufs: core: Add CPU latency QoS support for ufs driver To: Manivannan Sadhasivam , Bart Van Assche CC: Naresh Maramaina , "James E.J. Bottomley" , "Martin K. Petersen" , Peter Wang , Andy Gross , "Bjorn Andersson" , Konrad Dybcio , Matthias Brugger , AngeloGioacchino Del Regno , , "Alim Akhtar" , Avri Altman , , , , , , , References: <20231204143101.64163-1-quic_mnaresh@quicinc.com> <20231204143101.64163-2-quic_mnaresh@quicinc.com> <590ade27-b4da-49be-933b-e9959aa0cd4c@acm.org> <692cd503-5b14-4be6-831d-d8e9c282a95e@quicinc.com> <5e7c5c75-cb5f-4afe-9d57-b0cab01a6f26@acm.org> <20231206153242.GI12802@thinkpad> <20231207094357.GI2932@thinkpad> Content-Language: en-US From: Nitin Rawat In-Reply-To: <20231207094357.GI2932@thinkpad> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: xV9ZucUUu1VnH6KXAtu8Z4m5o650ce8x X-Proofpoint-GUID: xV9ZucUUu1VnH6KXAtu8Z4m5o650ce8x X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-07_08,2023-12-06_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 mlxscore=0 priorityscore=1501 suspectscore=0 malwarescore=0 lowpriorityscore=0 phishscore=0 impostorscore=0 clxscore=1011 bulkscore=0 spamscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2312070084 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/7/2023 3:13 PM, Manivannan Sadhasivam wrote: > On Wed, Dec 06, 2023 at 03:02:04PM -1000, Bart Van Assche wrote: >> On 12/6/23 05:32, Manivannan Sadhasivam wrote: >>> On Wed, Dec 06, 2023 at 07:32:54PM +0530, Naresh Maramaina wrote: >>>> On 12/5/2023 10:41 PM, Bart Van Assche wrote: >>>>> On 12/4/23 21:58, Naresh Maramaina wrote: >>>>>> On 12/5/2023 12:30 AM, Bart Van Assche wrote: >>>>>>> On 12/4/23 06:30, Maramaina Naresh wrote: >>>>>>>> +    /* This capability allows the host controller driver to >>>>>>>> use the PM QoS >>>>>>>> +     * feature. >>>>>>>> +     */ >>>>>>>> +    UFSHCD_CAP_PM_QOS                = 1 << 13, >>>>>>>>   }; >>>>>>> >>>>>>> Why does it depend on the host driver whether or not PM QoS is >>>>>>> enabled? Why isn't it enabled unconditionally? >>>>>> >>>>>> For some platform vendors power KPI might be more important than >>>>>> random io KPI. Hence this flag is disabled by default and can be >>>>>> enabled based on platform requirement. >>>>> >>>>> How about leaving this flag out unless if a host vendor asks explicitly >>>>> for this flag? >>>> >>>> IMHO, instead of completely removing this flag, how about having >>>> flag like "UFSHCD_CAP_DISABLE_PM_QOS" which will make PMQOS enable >>>> by default and if some host vendor wants to disable it explicitly, >>>> they can enable that flag. >>>> Please let me know your opinion. >> >> That would result in a flag that is tested but that is never set by >> upstream code. I'm not sure that's acceptable. >> > > Agree. The flag shouldn't be introduced if there are no users. > >>> If a vendor wants to disable this feature, then the driver has to be modified. >>> That won't be very convenient. So either this has to be configured through sysfs >>> or Kconfig if flexibility matters. >> >> Kconfig sounds worse to me because changing any Kconfig flag requires a >> modification of the Android GKI kernel. >> > > Hmm, ok. Then I think we can have a sysfs hook to toggle the enable switch. Hi Bart, Mani How about keeping this feature enabled by default and having a module parameter to disable pmqos feature if required ? Regards, Nitin > > - Mani > >> Thanks, >> >> Bart. >