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 X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4ED37C63798 for ; Wed, 25 Nov 2020 15:50:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF999205CB for ; Wed, 25 Nov 2020 15:50:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="rfvmEQey" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730682AbgKYPtr (ORCPT ); Wed, 25 Nov 2020 10:49:47 -0500 Received: from m42-4.mailgun.net ([69.72.42.4]:39334 "EHLO m42-4.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730557AbgKYPtr (ORCPT ); Wed, 25 Nov 2020 10:49:47 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1606319386; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: References: Cc: To: From: Subject: Sender; bh=7iwAdiFg/usLX+g7/HJGxHhH4j10I+t6/oKyk/C1ilc=; b=rfvmEQey7JL0s/xeF3VP5bTbkhiSBkWBwSSrIXCQebD1ndRGWEU9NskMNNn0d+lo15JEBdnO 5v1ye2fiTUZ8eqos2Tgo4dYMtaaL0LShNCg1QVJO+0EB1+4rG0ldEYmVUf+wWW2+uGTRmPoA 5mV621DTWr84Y7W0E2YdKcHWuTM= X-Mailgun-Sending-Ip: 69.72.42.4 X-Mailgun-Sid: WyI1MzIzYiIsICJsaW51eC1hcm0tbXNtQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n03.prod.us-east-1.postgun.com with SMTP id 5fbe7d13b9b39088ed7e5f08 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 25 Nov 2020 15:49:39 GMT Sender: jhugo=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 5880FC43462; Wed, 25 Nov 2020 15:49:38 +0000 (UTC) Received: from [10.226.59.216] (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: jhugo) by smtp.codeaurora.org (Postfix) with ESMTPSA id 0AB9CC433C6; Wed, 25 Nov 2020 15:49:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 0AB9CC433C6 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=jhugo@codeaurora.org Subject: Re: [PATCH] bus: mhi: core: Indexed MHI controller name From: Jeffrey Hugo To: Loic Poulain , manivannan.sadhasivam@linaro.org, hemantk@codeaurora.org Cc: linux-arm-msm@vger.kernel.org References: <1606318983-24898-1-git-send-email-loic.poulain@linaro.org> <1093835e-3ed6-5579-5fbe-39a6d8fbadaf@codeaurora.org> Message-ID: <005093de-c8e4-2075-050a-5998a3cbcfcc@codeaurora.org> Date: Wed, 25 Nov 2020 08:49:36 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <1093835e-3ed6-5579-5fbe-39a6d8fbadaf@codeaurora.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 11/25/2020 8:42 AM, Jeffrey Hugo wrote: > On 11/25/2020 8:43 AM, Loic Poulain wrote: >> Today the MHI controller name is simply cloned from the underlying >> bus device (its parent), that gives the following device structure >> for e.g. a MHI/PCI controller: >> devices/pci0000:00/0000:00:01.2/0000:02:00.0/0000:02:00.0 >> devices/pci0000:00/0000:00:01.2/0000:02:00.0/0000:02:00.0/0000:02:00.0_IPCR >> >> ... >> >> That's quite misleading/confusing and can cause device registering >> issues because of duplicate dev name (e.g. if a PCI device register >> two different MHI instances). >> >> This patch changes MHI core to create indexed mhi controller names >> (mhi0, mhi1...) in the same way as other busses (i2c0, usb0...). >> >> The previous example becomes: >> devices/pci0000:00/0000:00:01.2/0000:02:00.0/mhi0 >> devices/pci0000:00/0000:00:01.2/0000:02:00.0/mhi0/mhi0_IPCR >> ... >> >> Signed-off-by: Loic Poulain > > > How does this change /sys/bus/mhi/devices/ ? > > The point of having the bus name in the mhi device name is to give an > easy way to correlate those devices back to the "root" device (I have a > lot of users which do that). > > Also, do we actually have some device that actually exposes multiple MHI > interfaces? > > Looking at the code change itself, looks like the controller index is essentially random, and not persistent. Is that expected? I'm thinking it might be confusing if you have say 12 MHI controllers from 12 different devices, and some of those devices crash at roughly the same time. The controllers get removed, and re-initialized, which means that you have essentially a race condition where the controller for the same device now has a different index. -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.