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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 50749C433E0 for ; Sun, 10 Jan 2021 16:29:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A80822573 for ; Sun, 10 Jan 2021 16:29:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726265AbhAJQ3A (ORCPT ); Sun, 10 Jan 2021 11:29:00 -0500 Received: from netrider.rowland.org ([192.131.102.5]:34049 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1726228AbhAJQ3A (ORCPT ); Sun, 10 Jan 2021 11:29:00 -0500 Received: (qmail 1161744 invoked by uid 1000); 10 Jan 2021 11:28:18 -0500 Date: Sun, 10 Jan 2021 11:28:18 -0500 From: Alan Stern To: Eugene Korenevsky Cc: linux-usb@vger.kernel.org, Greg Kroah-Hartman Subject: Re: [PATCH v5] ehci: fix EHCI host controller initialization sequence Message-ID: <20210110162818.GA1161376@rowland.harvard.edu> References: <20210110092146.GA12790@himera.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210110092146.GA12790@himera.home> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Sun, Jan 10, 2021 at 12:21:47PM +0300, Eugene Korenevsky wrote: > According to EHCI spec, EHCI HC clears USBSTS.HCHalted whenever > USBCMD.RS=1. > > However, it is a good practice to wait some time after setting USBCMD.RS > (approximately 100ms) until USBSTS.HCHalted become zero. > > Without this waiting, VirtualBox's EHCI virtual HC accidentally hangs > (see BugLink). > > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=211095 > Signed-off-by: Eugene Korenevsky Acked-by: Alan Stern > --- > v1: initial patch > v2: add BugLink tag > v3: add Revieved-By tags (incorrect), restore `msleep(5)` > v4: remove Reviewed-By tags, restore reading from USBCMD prior to msleep, > adjust description > v5: add `patch changelog` > > drivers/usb/host/ehci-hcd.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c > index e358ae17d51e..1926b328b6aa 100644 > --- a/drivers/usb/host/ehci-hcd.c > +++ b/drivers/usb/host/ehci-hcd.c > @@ -574,6 +574,7 @@ static int ehci_run (struct usb_hcd *hcd) > struct ehci_hcd *ehci = hcd_to_ehci (hcd); > u32 temp; > u32 hcc_params; > + int rc; > > hcd->uses_new_polling = 1; > > @@ -629,9 +630,20 @@ static int ehci_run (struct usb_hcd *hcd) > down_write(&ehci_cf_port_reset_rwsem); > ehci->rh_state = EHCI_RH_RUNNING; > ehci_writel(ehci, FLAG_CF, &ehci->regs->configured_flag); > + > + /* Wait until HC become operational */ > ehci_readl(ehci, &ehci->regs->command); /* unblock posted writes */ > msleep(5); > + rc = ehci_handshake(ehci, &ehci->regs->status, STS_HALT, 0, 100 * 1000); > + > up_write(&ehci_cf_port_reset_rwsem); > + > + if (rc) { > + ehci_err(ehci, "USB %x.%x, controller refused to start: %d\n", > + ((ehci->sbrn & 0xf0)>>4), (ehci->sbrn & 0x0f), rc); > + return rc; > + } > + > ehci->last_periodic_enable = ktime_get_real(); > > temp = HC_VERSION(ehci, ehci_readl(ehci, &ehci->caps->hc_capbase)); > -- > 2.20.1