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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 90F83C47076 for ; Fri, 21 May 2021 18:06:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 75334613D0 for ; Fri, 21 May 2021 18:06:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238525AbhEUSHl (ORCPT ); Fri, 21 May 2021 14:07:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:57340 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238505AbhEUSHj (ORCPT ); Fri, 21 May 2021 14:07:39 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 15A51613CB; Fri, 21 May 2021 18:06:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621620375; bh=PGlP4iraJhEmtFARuI90AqejPX1/fQS9paNMLEY2w+Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iz450FZH/5bpTdyYLCWpyUOLw72CFhgN2ndPP3/YgWcYOR8Jkfl95UxlVx/K+Av6g f5ijoFD/NawtnO+gJA2BAiHN2iZROdpHLjIyjMrHUXwB+/hR6E53cP3Qk/wowOSo+B a4bUrLbrIfYkcP4jIqjDPr38Ofe7e4S+HAie+dPE= Date: Fri, 21 May 2021 20:06:13 +0200 From: Greg Kroah-Hartman To: Thierry Reding Cc: Chunfeng Yun , Liam Girdwood , Mark Brown , Matthias Brugger , Paul Cercueil , Lee Jones , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: Re: [PATCH v2 3/3] Revert "usb: common: usb-conn-gpio: Make VBUS supply optional" Message-ID: References: <1621406386-18838-1-git-send-email-chunfeng.yun@mediatek.com> <1621406386-18838-3-git-send-email-chunfeng.yun@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 21, 2021 at 03:20:23PM +0200, Thierry Reding wrote: > On Wed, May 19, 2021 at 02:39:46PM +0800, Chunfeng Yun wrote: > > Vbus is already an optional supply, if the vbus-supply is not > > provided in DTS, will use a dummy regulator, > > That statement is not entirely correct. The dummy regulator is > substituted only if the supply is in fact not optional. The idea behind > that is to allow DTS files that don't specify all required regulators to > get away with it, based on the assumption that the supply is one of > those always-on supplies that are often not described in DTS. > > > the warning log is as below: > > "supply vbus not found, using dummy regulator" > > And the reason why we get that warning is to point out that the DTS has > a bug and that it should be fixed (by adding a proper regulator to take > the place of the dummy). > > > This reverts commit 4ddf1ac79e5f082451cd549283d2eb7559ab6ca9. > > But if you read the description of that commit, the purpose of that > patch was in fact to make the supply completely optional in the case > where we already have the VBUS supply specified for the USB port that > the connector is parented to. > > So in that case the DTS doesn't have the bug because the VBUS supply is > already specified for the USB port and therefore it doesn't have to be > specified in the USB connector again. In fact, specifying it twice can > lead to a situation where the USB port may not be able to switch the > VBUS supply on or off because the setting might conflict with that of > the USB connector. > > So unless there's a real reason why this is needed, I don't think this > should be applied. I've dropped this from my tree now, thanks. greg k-h