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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B51DC43334 for ; Thu, 16 Jun 2022 17:15:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378092AbiFPRPy (ORCPT ); Thu, 16 Jun 2022 13:15:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357934AbiFPRPx (ORCPT ); Thu, 16 Jun 2022 13:15:53 -0400 Received: from mail-pf1-x42c.google.com (mail-pf1-x42c.google.com [IPv6:2607:f8b0:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79781483BA for ; Thu, 16 Jun 2022 10:15:52 -0700 (PDT) Received: by mail-pf1-x42c.google.com with SMTP id i64so2045132pfc.8 for ; Thu, 16 Jun 2022 10:15:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=8iz7ZOP2b0Lu2YomGWoPhULSTDfxHvkkUN5CEYP8CaU=; b=ApbDEiT1anUGxolRWQpnvh/eWWi46u0atckjEWb4RvkiaIAvr5aZnD+S+CE8pBh9Ue Rdpxdb8HpapM2i4wnBLme8kKJb6sQYtoE4BEIjrGkPuWRCm9/6eujrfB5IdbFD4FbxFh vlk2TjuD/1Sg2MIO0AkpoHPXrnb4FsWtTK2vc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=8iz7ZOP2b0Lu2YomGWoPhULSTDfxHvkkUN5CEYP8CaU=; b=Nw6NMCKplNLavq1M2REFd9ObwH3jkVo0eTz87VkRG2Gybm2y6EfDx1bAX5kXyeyhHY 37+TxhdK2dkfwKkTwI2g1elQuGINM1KvI25KZve5EsNDPdVIu7v0yx2xWHp89rN39L2V HBzFSM3X/yEhLQNkJ+ui8qAm7Qi1NsD3v7jCJtHR10236Q7NxIztLnAe57fRi2DI6gqA DI1MKkZhCLgbXl1dv+gwTEmS9KAiDyb+XJu21A4nzDuyW6KKAZiKIPR21xn+W4mrODzq eQsPXes6xeJdg8FgvTmgDUv4oHNMhRDSFMGgUyAUM4bFKs6xNiuS1xKz8ZgSsBdyfv6u e28w== X-Gm-Message-State: AJIora97BmCKmt19Aw+Ro5Mv+4/yHk8/2STif2HCsAgw3t6GHxzzIMca Ae5J5N08A3OfTOagm7zNoVLIOA== X-Google-Smtp-Source: AGRyM1v1gOcNbulVWr4yT4FU7oeqvsT8pT39TN0Lj/5MQsCXzknBAbpphcjXQ9hhBxZQMW11jlfYIw== X-Received: by 2002:a65:588b:0:b0:3fe:4237:2ee5 with SMTP id d11-20020a65588b000000b003fe42372ee5mr5334297pgu.442.1655399751849; Thu, 16 Jun 2022 10:15:51 -0700 (PDT) Received: from localhost ([2620:15c:11a:202:4ef5:7e3b:63ba:fc4]) by smtp.gmail.com with UTF8SMTPSA id j1-20020a170903028100b00164097a779fsm1891067plr.147.2022.06.16.10.15.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Jun 2022 10:15:51 -0700 (PDT) Date: Thu, 16 Jun 2022 10:15:49 -0700 From: Matthias Kaehlcke To: Pavan Kondeti Cc: Krishna Kurapati , Krzysztof Kozlowski , Rob Herring , Andy Gross , Bjorn Andersson , Greg Kroah-Hartman , Felipe Balbi , Stephen Boyd , Doug Anderson , Mathias Nyman , devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, quic_ppratap@quicinc.com, quic_vpulyala@quicinc.com Subject: Re: [PATCH v20 2/5] usb: dwc3: core: Host wake up support from system suspend Message-ID: References: <1654158277-12921-1-git-send-email-quic_kriskura@quicinc.com> <1654158277-12921-3-git-send-email-quic_kriskura@quicinc.com> <20220616091110.GA24114@hu-pkondeti-hyd.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220616091110.GA24114@hu-pkondeti-hyd.qualcomm.com> Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Thu, Jun 16, 2022 at 02:41:10PM +0530, Pavan Kondeti wrote: > Hi Matthias/Krishna, > > On Tue, Jun 14, 2022 at 10:53:35AM -0700, Matthias Kaehlcke wrote: > > On Mon, Jun 13, 2022 at 11:08:32AM -0700, Matthias Kaehlcke wrote: > > > On Mon, Jun 06, 2022 at 01:45:51PM -0700, Matthias Kaehlcke wrote: > > > > On Thu, Jun 02, 2022 at 12:35:42PM -0700, Matthias Kaehlcke wrote: > > > > > Hi Krishna, > > > > > > > > > > with this version I see xHCI errors on my SC7180 based system, like > > > > > these: > > > > > > > > > > [ 65.352605] xhci-hcd xhci-hcd.13.auto: xHC error in resume, USBSTS 0x401, Reinit > > > > > > > > > > [ 101.307155] xhci-hcd xhci-hcd.13.auto: WARN: xHC CMD_RUN timeout > > > > > > > > > > After resume a downstream hub isn't enumerated again. > > > > > > > > > > So far I didn't see those with v13, but I aso saw the first error with > > > > > v16. > > > > > > > > It also happens with v13, but only when a wakeup capable vUSB <= 2 > > > > device is plugged in. Initially I used a wakeup capable USB3 to > > > > Ethernet adapter to trigger the wakeup case, however older versions > > > > of this series that use usb_wakeup_enabled_descendants() to check > > > > for wakeup capable devices didn't actually check for vUSB > 2 > > > > devices. > > > > > > > > So the case were the controller/PHYs is powered down works, but > > > > the controller is unhappy when the runtime PM path is used during > > > > system suspend. > > > > > > The issue isn't seen on all systems using dwc3-qcom and the problem starts > > > during probe(). The expected probe sequence is something like this: > > > > > > dwc3_qcom_probe > > > dwc3_qcom_of_register_core > > > dwc3_probe > > > > > > if (device_can_wakeup(&qcom->dwc3->dev)) > > > ... > > > > > > The important part is that device_can_wakeup() is called after dwc3_probe() > > > has completed. That's what I see on a QC SC7280 system, where wakeup is > > > generally working with these patches. > > > > > > However on a QC SC7180 system dwc3_probe() is deferred and only executed after > > > dwc3_qcom_probe(). As a result the device_can_wakeup() call returns false. > > > With that the controller/driver ends up in an unhappy state after system > > > suspend. > > > > > > Probing is deferred on SC7180 because device_links_check_suppliers() finds > > > that '88e3000.phy' isn't ready yet. > > > > It seems device links could be used to make sure the dwc3 core is present: > > > > Another example for an inconsistent state would be a device link that > > represents a driver presence dependency, yet is added from the consumer’s > > ->probe callback while the supplier hasn’t probed yet: Had the driver core > > known about the device link earlier, it wouldn’t have probed the consumer > > in the first place. The onus is thus on the consumer to check presence of > > the supplier after adding the link, and defer probing on non-presence. > > > > https://www.kernel.org/doc/html/v5.18/driver-api/device_link.html#usage > > > > > > You could add something like this to dwc3_qcom_of_register_core(): > > > > > > device_link_add(dev, &qcom->dwc3->dev, > > DL_FLAG_AUTOREMOVE_CONSUMER | DL_FLAG_AUTOPROBE_CONSUMER); > > > > if (qcom->dwc3->dev.links.status != DL_DEV_DRIVER_BOUND) > > ret = -EPROBE_DEFER; > > > > > I am not very sure how the device_link_add() API works. we are the parent and > creating a depdency on child probe. That does not sound correct to me. The functional dependency is effectively there, the driver already assumes that the dwc3 core was probed when of_platform_populate() returns. The device link itself doesn't create the dependency on the probe(), the check of the link status below does. Another option would be to add a link to the PHYs to the dwc3-qcom node in the device tree, but I don't think that would be a better solution (and I expect Rob would oppose this). I'm open to other solutions, so far the device link is the cleanest that came to my mind. I think the root issue is the driver architecture, with two interdependent drivers for the same IP block, instead of a single framework driver with a common part (dwc3 core) and vendor specific hooks/data. > Any ways, I have another question. > > When dwc3_qcom_of_register_core() returns error back to dwc3_qcom_probe(), we > goto depopulate label which calls of_platform_depopulate() which destroy the > child devices that are populated. how does that ensure that child probe is > completed by the time, our probe is called again. The child device it self is > gone. Is this working because when our probe is called next time, the child > probe depenencies are resolved? Good point! It doesn't really ensure that the child is probed (actually it won't be probed and DL_FLAG_AUTOPROBE_CONSUMER doesn't make sense here), it could happen that dwc3_qcom_probe() is deferred multiple times, but eventually the PHYs should be ready and dwc3_probe() be invoked through of_platform_populate().