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=-5.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 DF0BDC64E7B for ; Tue, 1 Dec 2020 20:49:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 80052221E2 for ; Tue, 1 Dec 2020 20:49:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="kcFQfEN+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727892AbgLAUt2 (ORCPT ); Tue, 1 Dec 2020 15:49:28 -0500 Received: from m42-5.mailgun.net ([69.72.42.5]:15187 "EHLO m42-5.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727915AbgLAUt0 (ORCPT ); Tue, 1 Dec 2020 15:49:26 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1606855746; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=Yo42yaq/01Dx0rVkGb727su6dur/zrnh3T7p2hY8vMQ=; b=kcFQfEN+wEfV5C/YM/R96NQfEHIgbDusLXUUBpGgGWl+kL6UXH+PTGeTc/DtqXpq4Iv06weY s5TRD68SvHgYXqDJlOOQIR7NfR8cCFZqebJ2o/mhhoQBFrDqhExG0IvBTdnG/zZLEu1Fmaj+ j/niW5qm6ZVhin/jvgf+J6uGWkU= X-Mailgun-Sending-Ip: 69.72.42.5 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n08.prod.us-east-1.postgun.com with SMTP id 5fc6ac28f4482b01c4fbdf7e (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 01 Dec 2020 20:48:40 GMT Sender: jhugo=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 3DC4CC43462; Tue, 1 Dec 2020 20:48:39 +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 91A89C433ED; Tue, 1 Dec 2020 20:48:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 91A89C433ED 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 v13 0/4] userspace MHI client interface driver To: Jakub Kicinski Cc: Hemant Kumar , manivannan.sadhasivam@linaro.org, gregkh@linuxfoundation.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, bbhatt@codeaurora.org, loic.poulain@linaro.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, Kalle Valo References: <1606533966-22821-1-git-send-email-hemantk@codeaurora.org> <20201201112901.7f13e26c@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com> <20201201120302.474d4c9b@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com> From: Jeffrey Hugo Message-ID: <817a4346-efb7-cfe5-0678-d1b60d06627d@codeaurora.org> Date: Tue, 1 Dec 2020 13:48:36 -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: <20201201120302.474d4c9b@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com> 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-kernel@vger.kernel.org On 12/1/2020 1:03 PM, Jakub Kicinski wrote: > On Tue, 1 Dec 2020 12:40:50 -0700 Jeffrey Hugo wrote: >> On 12/1/2020 12:29 PM, Jakub Kicinski wrote: >>> On Fri, 27 Nov 2020 19:26:02 -0800 Hemant Kumar wrote: >>>> This patch series adds support for UCI driver. UCI driver enables userspace >>>> clients to communicate to external MHI devices like modem and WLAN. UCI driver >>>> probe creates standard character device file nodes for userspace clients to >>>> perform open, read, write, poll and release file operations. These file >>>> operations call MHI core layer APIs to perform data transfer using MHI bus >>>> to communicate with MHI device. Patch is tested using arm64 based platform. >>> >>> Wait, I thought this was for modems. >>> >>> Why do WLAN devices need to communicate with user space? >>> >> >> Why does it matter what type of device it is? Are modems somehow unique >> in that they are the only type of device that userspace is allowed to >> interact with? > > Yes modems are traditionally highly weird and require some serial > device dance I don't even know about. > > We have proper interfaces in Linux for configuring WiFi which work > across vendors. Having char device access to WiFi would be a step > back. So a WLAN device is only ever allowed to do Wi-Fi? It can't also have GPS functionality for example? > >> However, I'll bite. Once such usecase would be QMI. QMI is a generic >> messaging protocol, and is not strictly limited to the unique operations >> of a modem. >> >> Another usecase would be Sahara - a custom file transfer protocol used >> for uploading firmware images, and downloading crashdumps. > > Thanks, I was asking for use cases, not which proprietary vendor > protocol you can implement over it. > > None of the use cases you mention here should require a direct FW - > user space backdoor for WLAN. Uploading runtime firmware, with variations based on the runtime mode. Flashing the onboard flash based on cryptographic keys. Accessing configuration data. Accessing device logs. Configuring device logs. Synchronizing the device time reference to Linux local or remote time sources. Enabling debugging/performance hardware. Getting software diagnostic events. Configuring redundancy hardware per workload. Uploading new cryptographic keys. Invalidating cryptographic keys. Uploading factory test data and running factory tests. Need more? -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.