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 E93E5C63798 for ; Wed, 25 Nov 2020 16:24:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8EBEF207BC for ; Wed, 25 Nov 2020 16:24:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="n9RB3AFf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730650AbgKYQYS (ORCPT ); Wed, 25 Nov 2020 11:24:18 -0500 Received: from z5.mailgun.us ([104.130.96.5]:11632 "EHLO z5.mailgun.us" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730747AbgKYQYP (ORCPT ); Wed, 25 Nov 2020 11:24:15 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1606321454; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=0E8qFLAmA+eGllebKkYc7JS9X1MoOk7ANyTbIF7qlVo=; b=n9RB3AFf8tWv6/ZDVElifjy11XjAg5WCi9q+4A+8Tm8bl+FGaxy+DYQB2yUnd/nnHW96vgWM i/K6UFdMgp4v1wmVe8m/O2KzJrzOhe9cGZ+iIxORdw6koHrjxsfreLNYHYQ/RWbQwn+vH31F A7u7cuLPcIPtqmB+0y6o36QqW4A= X-Mailgun-Sending-Ip: 104.130.96.5 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-n09.prod.us-west-2.postgun.com with SMTP id 5fbe85277e9d874dfc45f03e (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 25 Nov 2020 16:24:07 GMT Sender: jhugo=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 30AD3C43460; Wed, 25 Nov 2020 16:24:07 +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 86FD4C433C6; Wed, 25 Nov 2020 16:24:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 86FD4C433C6 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 To: Loic Poulain Cc: Manivannan Sadhasivam , Hemant Kumar , linux-arm-msm References: <1606318983-24898-1-git-send-email-loic.poulain@linaro.org> <1093835e-3ed6-5579-5fbe-39a6d8fbadaf@codeaurora.org> From: Jeffrey Hugo Message-ID: <97494f35-2d00-9df9-a6f9-7ad69978f3cd@codeaurora.org> Date: Wed, 25 Nov 2020 09:24:04 -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: 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 9:15 AM, Loic Poulain wrote: > On Wed, 25 Nov 2020 at 16:42, 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/ ? > > That does change sysfs device dir names: > $ ls -al /sys/bus/mhi/devices/ > lrwxrwxrwx 1 root root 0 nov. 25 16:27 mhi0 -> > ../../../devices/pci0000:00/0000:00:01.2/0000:02:00.0/mhi0 > lrwxrwxrwx 1 root root 0 nov. 25 16:28 mhi0_DIAG -> > ../../../devices/pci0000:00/0000:00:01.2/0000:02:00.0/mhi0/mhi0_DIAG > lrwxrwxrwx 1 root root 0 nov. 25 16:28 mhi0_IPCR -> > ../../../devices/pci0000:00/0000:00:01.2/0000:02:00.0/mhi0/mhi0_IPCR > >> 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). > > I see your point but it's not a problem specific to MHI bus, user can > rely on sysfs/uevent to get device information such ass devices > attributes, children, or parent devices. Do you have a concrete > example in mind for your case? 3 I think - 1. I think its same to assume these names are going to trickle down to mhi_uci. For a QAIC device, there is a /dev/qaic chardev for doing the AI work, and a /dev chardev from mhi_uci exposing the DIAG channel. Both of these are correlated to a specific PCI device by the BDF, which the user application will want to know so that relevant DIAG traffic for a qaic device is routed to the correct chardev, and thus the correct device. For 1 device, this is simple. For 12, some correlation needs to be done programmatically. 2. User is physically on the shell, and wants to look at /sys/bus/mhi/devices to see the state of a device. Perhaps the expected mhi_uci devices are not present. 3. User is physically on the shell, and wants to invoke soc_reset on the controller. The user needs to know which mhi controller instance (mhi1?) maps to a specific PCI BDF to make sure the right device is reset. 1 is used a lot by our userspace stack. 2/3 is used a lot by testers and developers. > >> >> Also, do we actually have some device that actually exposes multiple MHI >> interfaces? > > No, but better to fix possible problems ahead of time. Good to know. I was thinking this was not needed, and unlikely to be needed, but it just occurs to me I might have a usecase for this in development. -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.