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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 A5ECBC0018C for ; Wed, 16 Dec 2020 09:11:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5048A2313B for ; Wed, 16 Dec 2020 09:11:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726248AbgLPJLg (ORCPT ); Wed, 16 Dec 2020 04:11:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47486 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726194AbgLPJLg (ORCPT ); Wed, 16 Dec 2020 04:11:36 -0500 Received: from mail-ed1-x536.google.com (mail-ed1-x536.google.com [IPv6:2a00:1450:4864:20::536]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96CB1C061794 for ; Wed, 16 Dec 2020 01:10:55 -0800 (PST) Received: by mail-ed1-x536.google.com with SMTP id q16so23988202edv.10 for ; Wed, 16 Dec 2020 01:10:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Cv2afJbDeZJNb1odPyKMoHfXMkCAGkNQaGWk4xDkS1Y=; b=aYow9Orkt22cpARMEbzczCYJF7d3nB8JC0mzA4kCpjQMSF8i1k5v9BLeSnmwvBWFzp cRzilpZhe2Hvvlfaw9vhCLO/h5Ig5nAIyBRN2k10KMKF6LH2KYgJP0gST9xCeaWoO8qO jFg4uFhuesKnSuW1FKLeV5P52pyg9I8v0wgtuGvR5aLOwZ0CrIyrJQPypZPwlUWTNSvB D6ZVFLOEUuktmmqWiBK7pBR2zeYAiP8Qe3EajqtTIlSoO1bGjIrJDRU8b9itrKo7Ne36 zsIe4WxfKf3M4jhs7ywJOHVKFXBYcXhnbxtVfeVuVC9PoMBquvarhPtisLTQ6xSD3qlm pWmg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Cv2afJbDeZJNb1odPyKMoHfXMkCAGkNQaGWk4xDkS1Y=; b=ubXrMF5DGI1tzaH1jkS47etSM1U2xPv4kdVTU7ORQ59S4GYqIhibbhBYfzBWnqWrXD sZDDdaZw01IxYzG4CKPSRyxZY2thXjD0b+FwhJlmZ/RD60A0MzYDoeBdiPi0UMKATi7Z QUuTmVI0/Kl+uS63n11s1cuO8SyiwFc8JU4kztjjfVSMStZG+Ijn3rftGre6P5g6HXna rjH968TWNkb1tFtY32NFjmXuVAzAfXA6SrMVLJEmFcCCzlYAWHg0oVKDaelHUqrbXjwg 9wQzKbcQBGoSogaSDxxzAlNBRJFt6Y7J0ySqiPu16luEf5VrsASh5g3XLkAjN5LJpBiI uuFQ== X-Gm-Message-State: AOAM532KBxWloIrcXCDYzy3hOU+ans9rVEeEfSWVLilfaG9QVonCvHxP 4pejVF9C/7RftceLAK1RxzkKqQHy/9ywB48d0IHitA== X-Google-Smtp-Source: ABdhPJxFZuRzgHup4J3bDTq8jdykkcC7HXin6/9clUn2PkjgwGRqVFRdsuFAyz33PC9ado3AZRofaKMAw0/+VM13K+M= X-Received: by 2002:aa7:dacf:: with SMTP id x15mr32490284eds.134.1608109853815; Wed, 16 Dec 2020 01:10:53 -0800 (PST) MIME-Version: 1.0 References: <1607715903-16442-1-git-send-email-hemantk@codeaurora.org> In-Reply-To: <1607715903-16442-1-git-send-email-hemantk@codeaurora.org> From: Loic Poulain Date: Wed, 16 Dec 2020 10:17:30 +0100 Message-ID: Subject: Re: [PATCH v18 0/3] userspace MHI client interface driver To: Manivannan Sadhasivam , Greg Kroah-Hartman , Jakub Kicinski Cc: linux-arm-msm , Hemant Kumar , open list , Jeffrey Hugo , Bhaumik Bhatt , Network Development Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Folks, On Fri, 11 Dec 2020 at 20:45, Hemant Kumar wrote: > > This patch series adds support for UCI driver. UCI driver enables userspace > clients to communicate to external MHI devices like modem. 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. > > This interface allows exposing modem control channel(s) such as QMI, MBIM, > or AT commands to userspace which can be used to configure the modem using > tools such as libqmi, ModemManager, minicom (for AT), etc over MHI. This is > required as there are no kernel APIs to access modem control path for device > configuration. Data path transporting the network payload (IP), however, is > routed to the Linux network via the mhi-net driver. Currently driver supports > QMI channel. libqmi is userspace MHI client which communicates to a QMI > service using QMI channel. Please refer to > https://www.freedesktop.org/wiki/Software/libqmi/ for additional information > on libqmi. > > Patch is tested using arm64 and x86 based platform. Are there any blockers or unadressed comments remaining on this series? As far as I understand, the original blocker was the net/WiFi mention in the commit message, that caused a legitimate concern from network maintainer. It has been clarified now that this driver is not for exposing any channel that could be otherwise handled properly by an existing Linux subsystem/interface. It will be especially used as a pipe for modem QMI channel (or AT commands) in the same way as the USB CDC-WDM driver is doing (keeping userspace compatibility). Other MHI channels, such as network data, QRTR, etc are not exposed and correctly bound to the corresponding Linux subsystems. The correlated worry was that it could be a userspace channel facility for 'everything qualcomm', but we could say the same for other existing busses with userspace shunt (/dev/bus/usb, /dev/i2c, /dev/spidev, PCI UIO, UART...). Moreover, it is mitigated by the fact that not all MHI channels are exposed by default, but only the allowed ones (QMI in the initial version). For sure, special care must be given to any further channel addition. Regards, Loic