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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 684FCC43460 for ; Fri, 9 Apr 2021 15:09:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35A54610A8 for ; Fri, 9 Apr 2021 15:09:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234094AbhDIPJ3 (ORCPT ); Fri, 9 Apr 2021 11:09:29 -0400 Received: from netrider.rowland.org ([192.131.102.5]:40409 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S233878AbhDIPJZ (ORCPT ); Fri, 9 Apr 2021 11:09:25 -0400 Received: (qmail 1334363 invoked by uid 1000); 9 Apr 2021 11:09:11 -0400 Date: Fri, 9 Apr 2021 11:09:11 -0400 From: Alan Stern To: Chunfeng Yun Cc: 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 Subject: Re: [RFC PATCH] usb: core: reduce power-on-good delay time of root hub Message-ID: <20210409150911.GC1333284@rowland.harvard.edu> References: <1617935947-24045-1-git-send-email-chunfeng.yun@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1617935947-24045-1-git-send-email-chunfeng.yun@mediatek.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 09, 2021 at 10:39:07AM +0800, Chunfeng Yun wrote: > Return the exactly delay time given by root hub descriptor, > this helps to reduce resume time etc. > > Due to the root hub descriptor is usually provided by the host > controller driver, if there is compatibility for a root hub, > we can fix it easily without affect other root hub > > Signed-off-by: Chunfeng Yun Acked-by: Alan Stern > --- > drivers/usb/core/hub.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h > index 73f4482d833a..22ea1f4f2d66 100644 > --- a/drivers/usb/core/hub.h > +++ b/drivers/usb/core/hub.h > @@ -148,8 +148,10 @@ static inline unsigned hub_power_on_good_delay(struct usb_hub *hub) > { > unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2; > > - /* Wait at least 100 msec for power to become stable */ > - return max(delay, 100U); > + if (!hub->hdev->parent) /* root hub */ > + return delay; > + else /* Wait at least 100 msec for power to become stable */ > + return max(delay, 100U); > } > > static inline int hub_port_debounce_be_connected(struct usb_hub *hub, > -- > 2.18.0 >