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=-4.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 B9ED1C04AB5 for ; Thu, 6 Jun 2019 08:17:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8C78620673 for ; Thu, 6 Jun 2019 08:17:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cogentembedded-com.20150623.gappssmtp.com header.i=@cogentembedded-com.20150623.gappssmtp.com header.b="riwQ1+rT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727129AbfFFIRK (ORCPT ); Thu, 6 Jun 2019 04:17:10 -0400 Received: from mail-lj1-f195.google.com ([209.85.208.195]:41212 "EHLO mail-lj1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727109AbfFFIRI (ORCPT ); Thu, 6 Jun 2019 04:17:08 -0400 Received: by mail-lj1-f195.google.com with SMTP id s21so1114802lji.8 for ; Thu, 06 Jun 2019 01:17:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cogentembedded-com.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=ms/3gXcMEPIWd0uNgXu5WibAfZ4H8Pur2jPfFPQc+aw=; b=riwQ1+rT5MbPfmvDMczw2lUSqrvicxWO50/VLtZVvnmRfXJ9OgR0n95tm2KkQymMYf 06Rpk+zBqPsrZNEl2s/bbndS5Pc53pHSG/YgrePU0vOZOfGF28+vl9moIpllPD1VG9HJ Q4Pvr+mlOuAvwX+m80S+32t7yOpJuNqmQRDkWxX4XHqj6NkHIOLp8Jf9VC12yHdKjytb hQZROzCHtOVPCr/oJdtvaUhRpXcRElgNaZB6o0qtj3GfCRpkj8NSmOvYaiIvnquT2DK1 Ne/suZjE8XizEOU988eK0Wk/Ru3tQot6icH91h0rS8w78Vh46t2QlN7Sr7LwGid5W/xZ EnDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=ms/3gXcMEPIWd0uNgXu5WibAfZ4H8Pur2jPfFPQc+aw=; b=g7d372gycIKbzbnn1DpqSreb+4i9Z12CIMA+JQRs/IKVvwnWN5NF9Yck4facDmNzDp 5rPOo261xgnJperxzCUWwEuLUN3mfA2/7ssrqvSoASVUFzy8o3HFvPMYg6yBDfs1lTD8 0TAVofOa4lTR3tLj2j+DzemdYmWS04ymOdH8VhREpkRwPGYCyAfBqN0K7lQTKTyqjVNW sl2CQFq7dPoNKknLo2RUSG4bw3+eHMH4lYpjKGxEzHoeNHY2+zNgidFA71Mrh+6j95B/ TY9xsVTGA1RtBIpJcC9mk4kCSKk5wJNaFXKGdiOUTP5A/tKW2KyS78GXlTP514CTXpgf RG5A== X-Gm-Message-State: APjAAAWIOJOIwwtTZ3/iSA717x1e2Y6U9bsT3iAOD76YY/ToBgAT/BDd sotWF+iMNnMfKzS4SjCqWtbTuXhjbG4= X-Google-Smtp-Source: APXvYqxZrmtys7SbLSVyK9cD454Jm14C5G5I1bB8ztL7yOCjFzh1w/hKLJQj1dHM824bhIF+XDzmKw== X-Received: by 2002:a2e:81c4:: with SMTP id s4mr11792430ljg.182.1559809025880; Thu, 06 Jun 2019 01:17:05 -0700 (PDT) Received: from [192.168.0.199] ([31.173.81.46]) by smtp.gmail.com with ESMTPSA id b25sm184051lff.42.2019.06.06.01.17.04 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Jun 2019 01:17:05 -0700 (PDT) Subject: Re: [RESEND][PATCH v3 1/2] usb: dwc3: Add avoiding vbus glitch happen during xhci reset To: Ran Wang , Greg Kroah-Hartman , Rob Herring , Mark Rutland , Felipe Balbi , Yang Li Cc: linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190606025418.26313-1-ran.wang_1@nxp.com> From: Sergei Shtylyov Message-ID: <78eb1558-b8d4-0632-ad0c-4144c711d2da@cogentembedded.com> Date: Thu, 6 Jun 2019 11:16:54 +0300 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190606025418.26313-1-ran.wang_1@nxp.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello! On 06.06.2019 5:54, Ran Wang wrote: > When DWC3 is set to host mode by programming register DWC3_GCTL, VBUS > (or its control signal) will turn on immediately on related Root Hub > ports. Then the VBUS will be de-asserted for a little while during xhci > reset (conducted by xhci driver) for a little while and back to normal. > > This VBUS glitch might cause some USB devices emuration fail if kernel Enumeration. :-) > boot with them connected. One SW workaround which can fix this is to > program all PORTSC[PP] to 0 to turn off VBUS immediately after setting > host mode in DWC3 driver(per signal measurement result, it will be too > late to do it in xhci-plat.c or xhci.c). > > Signed-off-by: Ran Wang > Reviewed-by: Rob Herring [...] MBR, Sergei