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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84FE7C433F5 for ; Wed, 3 Nov 2021 20:36:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6824F60EB4 for ; Wed, 3 Nov 2021 20:36:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230500AbhKCUit (ORCPT ); Wed, 3 Nov 2021 16:38:49 -0400 Received: from mga14.intel.com ([192.55.52.115]:28920 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229698AbhKCUis (ORCPT ); Wed, 3 Nov 2021 16:38:48 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10157"; a="231840605" X-IronPort-AV: E=Sophos;i="5.87,206,1631602800"; d="scan'208";a="231840605" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Nov 2021 13:36:11 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,206,1631602800"; d="scan'208";a="639057499" Received: from mattu-haswell.fi.intel.com (HELO [10.237.72.199]) ([10.237.72.199]) by fmsmga001.fm.intel.com with ESMTP; 03 Nov 2021 13:36:08 -0700 Subject: Re: [PATCH v2] usb: core: reduce power-on-good delay time of root hub To: "Walt Jr. Brake" , Alan Stern , Mathias Nyman Cc: Chunfeng Yun , Greg Kroah-Hartman , Matthias Brugger , Nishad Kamdar , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, Eddie Hung References: <1618017645-12259-1-git-send-email-chunfeng.yun@mediatek.com> <5e907ccd-40bb-2ece-fe05-1a65a74f3aa2@gmail.com> <20211101140613.GC1456700@rowland.harvard.edu> <3cf46eaf-5443-30df-6d72-b92a6a518afc@linux.intel.com> <62d0ac30-f2b9-f58c-cb1e-215ccb455753@gmail.com> From: Mathias Nyman Message-ID: <13d55059-9f66-8599-54fc-46698bae41d1@linux.intel.com> Date: Wed, 3 Nov 2021 22:37:33 +0200 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: <62d0ac30-f2b9-f58c-cb1e-215ccb455753@gmail.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 2.11.2021 22.29, Walt Jr. Brake wrote: > On 2/11/2021 17:05, Mathias Nyman wrote: >> On 1.11.2021 16.06, Alan Stern wrote: >>> On Sat, Oct 30, 2021 at 12:49:37PM +0800, Walt Jr. Brake wrote: >>>> This patch make USB 3.1 device cannot be detected, and I report the bug [1] >>>> to archlinux three month ago. Yesterday I try to fix it myself, and after I >>>> revert this patch, compile the kernel and test, it works. >>>> >>>> [1] https://bugs.archlinux.org/task/71660?project=1&pagenum=2 >>>> >>>> >>>> diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h >>>> index 22ea1f4f2d66..73f4482d833a 100644 >>>> --- a/drivers/usb/core/hub.h >>>> +++ b/drivers/usb/core/hub.h >>>> @@ -148,10 +148,8 @@ static inline unsigned hub_power_on_good_delay(struct >>>> usb_hub *hub) >>>>   { >>>>          unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2; >>>> >>>> -       if (!hub->hdev->parent) /* root hub */ >>>> -               return delay; >>>> -       else /* Wait at least 100 msec for power to become stable */ >>>> -               return max(delay, 100U); >>>> +       /* Wait at least 100 msec for power to become stable */ >>>> +       return max(delay, 100U); >>>>   } >>> Mathias: >>> >>> It looks like the bPwrOn2PwrGood value in xhci-hcd's hub descriptor is >>> too small for some USB 3.1 devices. >>> >>> Can you look into this? >>> >>> Alan Stern >>> >> At first glance the xhci roothub bPwrOn2PwrGood value looks ok. >> xhci spec 5.4.8 states software should wait 20ms after asserting PP, before >> attempting to change the state of the port. >> >> xhci driver sets desc->bPwrOn2PwrGood = 10; (2ms interval, so equals 20ms ) >> >> We should probably get this working immediately, so maybe revert that patch >> while looking into the rootcause. >> >> Walt Jr. Brake, instead of reverting that patch, could you test if changing the >> xhci roothub bPwrOn2PwrGood value helps. >> >> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c >> index a3f875eea751..756231a55602 100644 >> --- a/drivers/usb/host/xhci-hub.c >> +++ b/drivers/usb/host/xhci-hub.c >> @@ -257,7 +257,7 @@ static void xhci_common_hub_descriptor(struct xhci_hcd *xhci, >>   { >>          u16 temp; >>   -       desc->bPwrOn2PwrGood = 10;      /* xhci section 5.4.9 says 20ms max */ >> +       desc->bPwrOn2PwrGood = 50;      /* The 20ms in xhci 5.4.8 isn't enough for USB 3.1 */ >>          desc->bHubContrCurrent = 0; >>            desc->bNbrPorts = ports; >> >> Thanks >> -Mathias > > Mathias: > > Sorry to reply lately. I test with your patch, it works. > > I also test with setting bPwrOn2PwrGood to 45, and it not work. > > Seems that the minimal value should be 50 for this case. > Thanks for testing, and for checking that 90ms wait isn't enough -Mathias