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, URIBL_BLOCKED,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 51DF0C433DF for ; Sat, 4 Jul 2020 14:48:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 371F220885 for ; Sat, 4 Jul 2020 14:48:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726897AbgGDOsR (ORCPT ); Sat, 4 Jul 2020 10:48:17 -0400 Received: from netrider.rowland.org ([192.131.102.5]:35535 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1726573AbgGDOsR (ORCPT ); Sat, 4 Jul 2020 10:48:17 -0400 Received: (qmail 650547 invoked by uid 1000); 4 Jul 2020 10:48:16 -0400 Date: Sat, 4 Jul 2020 10:48:16 -0400 From: Alan Stern To: Peter Chen Cc: "mathias.nyman@intel.com" , "linux-usb@vger.kernel.org" , "gregkh@linuxfoundation.org" , dl-linux-imx Subject: Re: [PATCH 2/2] usb: host: xhci-plat: add wakeup entry at /sys Message-ID: <20200704144816.GA650205@rowland.harvard.edu> References: <20200703062532.29076-1-peter.chen@nxp.com> <20200703062532.29076-2-peter.chen@nxp.com> <20200703141911.GA623139@rowland.harvard.edu> <20200704092255.GA5695@b29397-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200704092255.GA5695@b29397-desktop> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Sat, Jul 04, 2020 at 09:22:45AM +0000, Peter Chen wrote: > On 20-07-03 10:19:11, Alan Stern wrote: > > On Fri, Jul 03, 2020 at 02:25:32PM +0800, Peter Chen wrote: > > > After that, the user could enable controller as wakeup source > > > for system suspend through /sys entry. > > > > > > Signed-off-by: Peter Chen > > > --- > > > drivers/usb/host/xhci-plat.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c > > > index cebe24ec80a5..bb5d73f0a796 100644 > > > --- a/drivers/usb/host/xhci-plat.c > > > +++ b/drivers/usb/host/xhci-plat.c > > > @@ -287,7 +287,7 @@ static int xhci_plat_probe(struct platform_device *pdev) > > > *priv = *priv_match; > > > } > > > > > > - device_wakeup_enable(hcd->self.controller); > > > + device_set_wakeup_capable(hcd->self.controller, true); > > > > > > In fact both this patch and the original code are wrong. It really should > > be: > > > > device_init_wakeup(hcd->self.controller, true); > > > > This will add the wakeup entry in sysfs and set it to Enabled. This is > > the appropriate behavior, as explained in the kerneldoc for > > device_init_wakeup(). The reason is because the controller device doesn't > > create any wakeup events on its own; it merely relays wakeup requests from > > descendant devices (root hubs or USB devices). > > Hi Alan, > > At xhci-plat.c's system suspend API xhci_plat_suspend, it depends on > power/wakeup value to determine whether the controller should enable > port wakeup capabilities, and from the system level, whether the system > supports USB wakeup or not is better to be determined by user, and is > disabled by default. > > Yes, you are right. The wakeup events are from controller's descendant > devices, and it is better to use roothub's wakeup capability to control > portsc's wakeup setting. At controller driver, the meaning for wakeup > setting is enabling wakeup interrupt for hardware signal events (dp/dm for USB2, > and RX-detect for USB3), this hardware logic is the glue layer and > designed by each vendors, without this logic, the USB controller can't > be woken up due to the USBCMD.RS bit is cleared, and there is no > standard EHCI or xHCI interrupt. The controller's wakeup setting is > better to be disabled by default, and decided by user too. > > For me, either this patch or use roothub's wakeup capability to > control portsc wakeup setting, both are OK. Mathias, what's your > opinion? Mathias is starting a long vacation, so he might not reply for a while. Note that hcd-pci.c, ohci-platform.c, and ehci-platform.c all call device_wakeup_enable(). This indicates that xhci-plat.c should do the same -- presumably device_set_wakeup_capable() is already called somewhere in the platform-specific code. There is a brief discussion about this in Documentation/driver-api/pm/devices.rst. Alan Stern