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 1DCC8C433EF for ; Mon, 1 Nov 2021 14:06:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E42BC6108F for ; Mon, 1 Nov 2021 14:06:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232426AbhKAOIu (ORCPT ); Mon, 1 Nov 2021 10:08:50 -0400 Received: from netrider.rowland.org ([192.131.102.5]:57455 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S229826AbhKAOIs (ORCPT ); Mon, 1 Nov 2021 10:08:48 -0400 Received: (qmail 1457560 invoked by uid 1000); 1 Nov 2021 10:06:13 -0400 Date: Mon, 1 Nov 2021 10:06:13 -0400 From: Alan Stern To: Mathias Nyman , "Walt Jr. Brake" 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 Subject: Re: [PATCH v2] usb: core: reduce power-on-good delay time of root hub Message-ID: <20211101140613.GC1456700@rowland.harvard.edu> References: <1618017645-12259-1-git-send-email-chunfeng.yun@mediatek.com> <5e907ccd-40bb-2ece-fe05-1a65a74f3aa2@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5e907ccd-40bb-2ece-fe05-1a65a74f3aa2@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > On 10/4/2021 09:20, 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 > > > > Acked-by: Alan Stern > > Signed-off-by: Chunfeng Yun > > --- > > v2: remove RFC tag, and add acked-by Alan > > --- > > 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,