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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 80C1AC33CB2 for ; Tue, 14 Jan 2020 14:46:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 61C4F2467E for ; Tue, 14 Jan 2020 14:46:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725904AbgANOqk (ORCPT ); Tue, 14 Jan 2020 09:46:40 -0500 Received: from mga14.intel.com ([192.55.52.115]:51924 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726106AbgANOqk (ORCPT ); Tue, 14 Jan 2020 09:46:40 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Jan 2020 06:46:39 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,433,1571727600"; d="scan'208";a="305163859" Received: from mattu-haswell.fi.intel.com (HELO [10.237.72.170]) ([10.237.72.170]) by orsmga001.jf.intel.com with ESMTP; 14 Jan 2020 06:46:36 -0800 Subject: Re: [PATCH 2/3] xhci: Wait until link state trainsits to U0 after setting USB_SS_PORT_LS_U0 To: Kai-Heng Feng Cc: Mathias Nyman , Greg Kroah-Hartman , Alan Stern , AceLan Kao , USB list , LKML References: <20200103084008.3579-1-kai.heng.feng@canonical.com> <20200103084008.3579-2-kai.heng.feng@canonical.com> <17701887-a249-eade-eecb-541df6c2c704@linux.intel.com> From: Mathias Nyman Message-ID: <7f6d4742-6e68-ea1d-4266-c69c27a19df6@linux.intel.com> Date: Tue, 14 Jan 2020 16:48:40 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 13.1.2020 11.18, Kai-Heng Feng wrote: > On Fri, Jan 10, 2020 at 11:27 PM Mathias Nyman > wrote: >> >> On 3.1.2020 10.40, Kai-Heng Feng wrote: >>> Like U3 case, xHCI spec doesn't specify the upper bound of U0 transition >>> time. The 20ms is not enough for some devices. >>> >>> Intead of polling PLS or PLC, we can facilitate the port change event to >>> know that the link transits to U0 is completed. >>> >>> Signed-off-by: Kai-Heng Feng >>> --- >>> drivers/usb/host/xhci-hub.c | 8 +++++++- >>> drivers/usb/host/xhci-mem.c | 1 + >>> drivers/usb/host/xhci-ring.c | 1 + >>> drivers/usb/host/xhci.h | 1 + >>> 4 files changed, 10 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c >>> index 2b2e9d004dbf..07886a1bce62 100644 >>> --- a/drivers/usb/host/xhci-hub.c >>> +++ b/drivers/usb/host/xhci-hub.c >>> @@ -1310,11 +1310,17 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue, >>> spin_lock_irqsave(&xhci->lock, flags); >>> } >>> } >>> + if (link_state == USB_SS_PORT_LS_U0) >>> + reinit_completion(&ports[wIndex]->link_state_changed); >> >> All the other suspend and resume related port flags/completions are >> in struct xhci_bus_state. See for example rexit_done[]. >> Not sure that is a better place but at least it would be consistent. >> >> Could actually make sense to move more of them to the xhci_port structure, >> but perhaps in some later suspend/resume rework patch. > > Ok. Should I keep this part of the patch as is? Or move it to > xhci_bus_state and probably move it back to xhci_port in later rework > patch? Maybe move it to xhci_bus_state for now. > >>> >>> xhci_set_link_state(xhci, ports[wIndex], link_state); >>> >>> spin_unlock_irqrestore(&xhci->lock, flags); >>> - msleep(20); /* wait device to enter */ >>> + if (link_state == USB_SS_PORT_LS_U0) { >>> + if (!wait_for_completion_timeout(&ports[wIndex]->link_state_changed, msecs_to_jiffies(100))) >>> + xhci_dbg(xhci, "missing U0 port change event for port %d-%d\n", hcd->self.busnum, wIndex + 1); >> >> We might be waiting for completion here in unnecessary. >> No completion is called if port is already in U0, either set by >> xhci_bus_resume(), or we race with a device initiated resume. > > Is there a way to know if device initiated resume is inplace? Yes, before xhci interrupt handler handles the device initiated resume PLS is XDEV_RESUME and PLC is set. After the interrupt handler PLS goes from XDEV_RESUME to XDEV_RECOVERY to XDEV_U0. A bit is set for bus_state->port_remote_wakeup, and on usb core side also bus->resuming_ports |= bit is set, (having both may be a bit redundant, we might be able to get rid of bus_state->port_remote_wakeup, but not right now) > >> >> Maybe read the current port link state first, and don't do anything if it's >> already in U0, or fail if it's in a state where we can't resume to U0. > > What happens if device initiated resume happens right after we query the PLS? Not sure, fortunately the drivers task is to write XDEV_U0 to PLS both when we want a host initiated resume, or when we want to react on a device initiated resume. So hopefully that's ok, but this race exists. Better keep calling completion for both host and device initiated resume cases when port reaches U0/U1/U2 to avoid waiting for the completion unnecessary, like you current patch does. -Mathias