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=-16.6 required=3.0 tests=BAYES_00, 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=unavailable 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 E0536C4320A for ; Tue, 24 Aug 2021 11:53:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C712861246 for ; Tue, 24 Aug 2021 11:53:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236909AbhHXLxt (ORCPT ); Tue, 24 Aug 2021 07:53:49 -0400 Received: from mga09.intel.com ([134.134.136.24]:14598 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236903AbhHXLxr (ORCPT ); Tue, 24 Aug 2021 07:53:47 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10085"; a="217297640" X-IronPort-AV: E=Sophos;i="5.84,347,1620716400"; d="scan'208";a="217297640" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2021 04:53:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,347,1620716400"; d="scan'208";a="473465551" Received: from mattu-haswell.fi.intel.com (HELO [10.237.72.170]) ([10.237.72.170]) by orsmga008.jf.intel.com with ESMTP; 24 Aug 2021 04:53:01 -0700 To: Kishon Vijay Abraham I , Greg Kroah-Hartman , Mathias Nyman , Alan Stern Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, chris.chiu@canonical.com References: <20210824105302.25382-1-kishon@ti.com> <20210824105302.25382-4-kishon@ti.com> From: Mathias Nyman Subject: Re: [RFC PATCH 3/5] usb: core: hcd: Add support for registering secondary RH along with primary HCD Message-ID: <06693934-28f2-d59e-b004-62cabd3f9e8e@linux.intel.com> Date: Tue, 24 Aug 2021 14:55:34 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210824105302.25382-4-kishon@ti.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24.8.2021 13.53, Kishon Vijay Abraham I wrote: > Add support for registering secondary roothub (RH) along with primary HCD. > It has been observed with certain PCIe USB cards that as soon as the > primary HCD is registered, port status change is handled leading to cold > plug devices getting not detected. For such cases, registering both the > root hubs along with the second HCD is useful. > > Signed-off-by: Kishon Vijay Abraham I > Suggested-by: Alan Stern > --- > drivers/usb/core/hcd.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c > index 4d7a9f0e2caa..9c8df22a7d9a 100644 > --- a/drivers/usb/core/hcd.c > +++ b/drivers/usb/core/hcd.c > @@ -2799,6 +2799,7 @@ int __usb_add_hcd(struct usb_hcd *hcd, unsigned int irqnum, unsigned long irqfla > { > int retval; > struct usb_device *rhdev; > + struct usb_hcd *shared_hcd = NULL; > > if (!hcd->skip_phy_initialization && usb_hcd_is_primary_hcd(hcd)) { > hcd->phy_roothub = usb_phy_roothub_alloc(hcd->self.sysdev); > @@ -2961,6 +2962,15 @@ int __usb_add_hcd(struct usb_hcd *hcd, unsigned int irqnum, unsigned long irqfla > > /* starting here, usbcore will pay attention to this root hub */ > if (register_hub) { > + shared_hcd = hcd->shared_hcd; > + if (shared_hcd) { > + retval = register_root_hub(shared_hcd); There is a possibility we try yo register the shared roothub before it is properly set up here. For example the mediatek driver (xhci-mtk.c) creates both hcds before adding them, so hcd->shared_hcd exists when usb_add_hcd() is called for the primary hcd, causing this code to register the hcd->shared_hcd roothub which is not properly added yet. How about skipping the new __usb_hcd_pci_probe() and __usb_add_hcd() and instead add a new flag to hcd->flags, something like HCD_FLAG_DEFER_PRI_RH_REGISTER? The host controller driver can set this flag in the hcd->driver->start(hcd) callback called before roothub registration here from usb_add_hcd(). If flag is set we skip the roothub registration. So something like: shared_hcd = hcd->share_hcd; if (!usb_hcd_is_primary_hcd(hcd) && shared_hcd && shared_hcd->flags & HCD_FLAG_DEFER_PRI_RH_REGISTER) register_root_hub(shared_hcd) if (!(hcd->flags & HCD_FLAG_DEFER_PRI_RH_REGISTER)) register_root_hub(hcd) -Mathias