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 3A62FC4332F for ; Tue, 31 Oct 2023 10:02:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235909AbjJaKCB (ORCPT ); Tue, 31 Oct 2023 06:02:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229653AbjJaKB7 (ORCPT ); Tue, 31 Oct 2023 06:01:59 -0400 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D693BF4 for ; Tue, 31 Oct 2023 03:01:56 -0700 (PDT) Received: from pps.filterd (m0279864.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 39V5gAKm030967; Tue, 31 Oct 2023 10:01:49 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=Oo9XyFjpyVq1Osw92ayqyJXAWzdnKmX8Jeobm+fYDT8=; b=A4QshcPODjOKgMWm91hN7BEFvLlpR5fa5S0KC3QQ2+Q/MnEJWgUWP1RYVDur/n7jpzql r/vfMd449Gqg+lKGEYRzaz5ZKp3ZVxUcyRcnrINToxM3V+IK+OrZVzkCiFtyxsKiU2EP eXxfzDewWfTb/egZUZpLB9WNm1AaIhSc1FqRDMlLdMcfzawblvX8n/mHB6JVoUZzkS49 521qmXN/NBZ+e1fEiucModc0fo1SKsGCSs2Jg9kDypoGu5c8ujfTjU5/0pWWiA0eFL++ YBI5jDDToRTAT0gYt9BBNVPFCoVXqZugx3B/qUff6fA4PZf7AHrFbHdzbQnfUPDqdzuz cw== Received: from nalasppmta01.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3u2egst9qg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 31 Oct 2023 10:01:48 +0000 Received: from nalasex01b.na.qualcomm.com (nalasex01b.na.qualcomm.com [10.47.209.197]) by NALASPPMTA01.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 39VA1m4r013412 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 31 Oct 2023 10:01:48 GMT Received: from [10.233.17.145] (10.80.80.8) by nalasex01b.na.qualcomm.com (10.47.209.197) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.39; Tue, 31 Oct 2023 03:01:46 -0700 Message-ID: Date: Tue, 31 Oct 2023 18:01:44 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: How to pass software configuration to driver built as module in boot up phase To: Greg Kroah-Hartman CC: Masami Hiramatsu , "Rafael J. Wysocki" , , Trilok Soni , Jinlong Mao References: <1c001c6f-9902-4803-9406-39e3325422bf@quicinc.com> <2023103021-revolving-clapper-632d@gregkh> <2023103108-guacamole-neurotic-f59b@gregkh> From: Tingwei Zhang In-Reply-To: <2023103108-guacamole-neurotic-f59b@gregkh> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01b.na.qualcomm.com (10.47.209.197) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: KD6-FdNVcJglCEtPkqnOUvFI0GuXo-W1 X-Proofpoint-GUID: KD6-FdNVcJglCEtPkqnOUvFI0GuXo-W1 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.987,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-10-30_13,2023-10-31_03,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 phishscore=0 mlxlogscore=902 adultscore=0 mlxscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 priorityscore=1501 spamscore=0 suspectscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2310240000 definitions=main-2310310078 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/31/2023 2:58 PM, Greg Kroah-Hartman wrote: > On Tue, Oct 31, 2023 at 10:56:23AM +0800, Tingwei Zhang wrote: >> On 10/30/2023 7:30 PM, Greg Kroah-Hartman wrote: >>> On Mon, Oct 30, 2023 at 07:21:48PM +0800, Tingwei Zhang wrote: >>>> Hi Masami, Greg and Rafael, >>>> >>>> I have one driver that needs a bunch to software configuration like 1000 >>>> settings. These settings can be different according to the use case. >>> >>> That seems very odd, what type of driver is this? >> The example use case is below DCC driver which is a DMA engine. It can be >> configured to read/write registers while whose registers need to be >> configured by software. It's mainly used to debug device crash issue. >> https://lore.kernel.org/lkml/cover.1691496290.git.quic_schowdhu@quicinc.com/T/ > > Given that no one listened to my last review cycle of that driver, why > are you asking us again? > There's some change on developer owner of DCC driver. We preparing and reviewing the driver internally. It will be submitted once ready. >>>> They are required in boot up phase so we can't reply on user space to make >>>> the configuration. >>>> >>>> Boot config is not preferred since we'd like to build that driver as dynamic >>>> load Kernel module. >>>> >>>> Could you let me know if there's any mechanism in Kernel to do that? >>> >>> What is wrong with the existing ways of doing this that all other >>> drivers use? >> I'm not aware of all the existing ways. Below ways are what I know and they >> may not be suitable for some reason. >> 1. Let user space to configure with sysfs/debugfs/ioctl interface. Since we >> need this configuration to be done in early stage before user space is up. > > I really doubt that you need this before userspace starts, as that's not > what "device crash" stuff should be dealing with. That happens after > init starts, because you have a working kernel (i.e. this is not for > hardware bringup.) > >> This doesn't work. > > Why do you need this before init? Specific reasons please. > There are some case that some driver broke Kernel in development phase and those bad driver could cause device crash in very early boot up phase. >> 2. Use device tree to pass the configuration to driver. Since the >> configuration is software configuration instead of hardware descirption. It >> doesn't fit in device tree. >> 3. Boot config or commandline parameter. If the driver is built in, it can >> work. But it doesn't work for dynamically loadable Kernel module. > > If you have a module, then you can do this after init starts, so you > are reporting conflicting "requirements" here, which make this > impossible for us to understand :( You are correct. I missed that part. We should already have user space up when install the module. > > Please work with the kernel developers at your company to come up with a > solution for this, you have the experience, do not require the community > to do your work for you. > > thanks, > > greg k-h -- Thanks, Tingwei