From patchwork Wed May 20 10:18:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kai-Heng Feng X-Patchwork-Id: 11559939 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6B31490 for ; Wed, 20 May 2020 10:18:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 51509207ED for ; Wed, 20 May 2020 10:18:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726785AbgETKSZ (ORCPT ); Wed, 20 May 2020 06:18:25 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:56499 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726688AbgETKSZ (ORCPT ); Wed, 20 May 2020 06:18:25 -0400 Received: from 61-220-137-37.hinet-ip.hinet.net ([61.220.137.37] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jbLnp-0001JH-UI; Wed, 20 May 2020 10:18:22 +0000 From: Kai-Heng Feng To: mathias.nyman@intel.com Cc: Kai-Heng Feng , Greg Kroah-Hartman , linux-usb@vger.kernel.org (open list:USB XHCI DRIVER), linux-kernel@vger.kernel.org (open list) Subject: [PATCH 2/2] xhci: Poll for U0 after disabling USB2 LPM Date: Wed, 20 May 2020 18:18:11 +0800 Message-Id: <20200520101811.2623-2-kai.heng.feng@canonical.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200520101811.2623-1-kai.heng.feng@canonical.com> References: <20200520101811.2623-1-kai.heng.feng@canonical.com> Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org USB2 devices with LPM enabled may interrupt the system suspend: [ 932.510475] usb 1-7: usb suspend, wakeup 0 [ 932.510549] hub 1-0:1.0: hub_suspend [ 932.510581] usb usb1: bus suspend, wakeup 0 [ 932.510590] xhci_hcd 0000:00:14.0: port 9 not suspended [ 932.510593] xhci_hcd 0000:00:14.0: port 8 not suspended .. [ 932.520323] xhci_hcd 0000:00:14.0: Port change event, 1-7, id 7, portsc: 0x400e03 .. [ 932.591405] PM: pci_pm_suspend(): hcd_pci_suspend+0x0/0x30 returns -16 [ 932.591414] PM: dpm_run_callback(): pci_pm_suspend+0x0/0x160 returns -16 [ 932.591418] PM: Device 0000:00:14.0 failed to suspend async: error -16 During system suspend, USB core will let HC suspends the device if it doesn't have remote wakeup enabled and doesn't have any children. However, from the log above we can see that the usb 1-7 doesn't get bus suspended due to not in U0. After a while the port finished U2 -> U0 transition, interrupts the suspend process. The observation is that after disabling LPM, port doesn't transit to U0 immediately and can linger in U2. xHCI spec 4.23.5.2 states that the maximum exit latency for USB2 LPM should be BESL + 10us. The BESL for the affected device is advertised as 400us, which is still not enough based on my testing result. So let's use the maximum permitted latency, 10000, to poll for U0 status to solve the issue. Signed-off-by: Kai-Heng Feng --- drivers/usb/host/xhci.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 14181a7ea375..1058f604975b 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -4474,6 +4474,9 @@ static int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd, mutex_lock(hcd->bandwidth_mutex); xhci_change_max_exit_latency(xhci, udev, 0); mutex_unlock(hcd->bandwidth_mutex); + readl_poll_timeout(ports[port_num]->addr, pm_val, + (pm_val & PORT_PLS_MASK) == XDEV_U0, + 100, 10000); return 0; } }