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=-15.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, 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 9D538C63798 for ; Tue, 24 Nov 2020 17:38:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 487AD20857 for ; Tue, 24 Nov 2020 17:38:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="FZxE8xHl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403873AbgKXRiA (ORCPT ); Tue, 24 Nov 2020 12:38:00 -0500 Received: from m42-4.mailgun.net ([69.72.42.4]:50725 "EHLO m42-4.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403870AbgKXRiA (ORCPT ); Tue, 24 Nov 2020 12:38:00 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1606239480; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=t7Lwuzy/Zx47k9drkP15FjSeAGYPsLyxKuQg5RQcorc=; b=FZxE8xHlOnBkMBPwaM9kxz/EQCrO3KiYoZVvi/XwIBQrKFczOrhm5sjArDzbxaN4xVrL8UNo 2EjKWr3XNaNhJC27y5ebNWCkND9AkEzru3m2Q8UNbJsdFoVIHTqI/f7vQzlhqiUFnIwf4rAO 0eWRlZ4AuZpz/q4cyMkDnv9xxHY= 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-west-2.postgun.com with SMTP id 5fbd44f11dba509aae5a0090 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 24 Nov 2020 17:37:53 GMT Sender: jhugo=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id D6493C43463; Tue, 24 Nov 2020 17:37:53 +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 2915EC433C6; Tue, 24 Nov 2020 17:37:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 2915EC433C6 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 v2] bus: mhi: core: Fix device hierarchy issue To: Loic Poulain Cc: Manivannan Sadhasivam , Hemant Kumar , linux-arm-msm , Bhaumik Bhatt References: <1606234711-20125-1-git-send-email-loic.poulain@linaro.org> From: Jeffrey Hugo Message-ID: Date: Tue, 24 Nov 2020 10:37:51 -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 11/24/2020 9:57 AM, Loic Poulain wrote: > On Tue, 24 Nov 2020 at 17:36, Jeffrey Hugo wrote: >> >> On 11/24/2020 9:18 AM, Loic Poulain wrote: >>> A MHI client device should be child of the MHI controller device. >>> Today both MHI controller and its MHI clients are direct children >>> of the same bus device. This patch fixes the hierarchy. >> >> Why? >> >> I'm not particularly arguing for or against this change (I think it >> affects me slightly, but not in a breaking way), but this commit text >> seems pretty generic. It doesn't really help me understand the >> relevance of this change. It seems to be only describing what you are >> doing, but not the why. How did you find this? How does this affect >> the client drivers? Does it make something the client drivers care >> about better? >> >> To put this another way, "should" is an opinion, and you've provided no >> facts to assert why your opinion is superior to others. > > That's right I've not elaborate too much, but it's mainly to respect > the hierarchy of devices, as it is done for other busses. The > hierarchy is especially important for things like power management > ordering (PM core must suspend devices before their controller, wakeup > the controller before its devices...). Moreover it will also be useful > for userspace (thanks to sysfs) to determine which devices are behind > which controllers (and so determine if e.g. QMI and IP channels are > part of the same device). This sounds like two relevant usecases which should be mentioned in the commit text. > > Regards, > Loic > > > >> >>> >>> Signed-off-by: Loic Poulain >>> --- >>> v2: fix commit message >>> >>> drivers/bus/mhi/core/init.c | 10 +++++++++- >>> 1 file changed, 9 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c >>> index 436221c..c7a7354 100644 >>> --- a/drivers/bus/mhi/core/init.c >>> +++ b/drivers/bus/mhi/core/init.c >>> @@ -1137,7 +1137,15 @@ struct mhi_device *mhi_alloc_device(struct mhi_controller *mhi_cntrl) >>> device_initialize(dev); >>> dev->bus = &mhi_bus_type; >>> dev->release = mhi_release_device; >>> - dev->parent = mhi_cntrl->cntrl_dev; >>> + >>> + if (mhi_cntrl->mhi_dev) { >>> + /* for MHI client devices, parent is the MHI controller device */ >>> + dev->parent = &mhi_cntrl->mhi_dev->dev; >>> + } else { >>> + /* for MHI controller device, parent is the bus device (e.g. pci device) */ >>> + dev->parent = mhi_cntrl->cntrl_dev; >>> + } >>> + >>> mhi_dev->mhi_cntrl = mhi_cntrl; >>> mhi_dev->dev_wake = 0; >>> >>> >> >> >> -- >> Jeffrey Hugo >> Qualcomm Technologies, Inc. is a member of the >> Code Aurora Forum, a Linux Foundation Collaborative Project. -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.