From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933062AbcHKIxy (ORCPT ); Thu, 11 Aug 2016 04:53:54 -0400 Received: from mail-pf0-f193.google.com ([209.85.192.193]:33013 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932656AbcHKIxt (ORCPT ); Thu, 11 Aug 2016 04:53:49 -0400 Date: Thu, 11 Aug 2016 16:44:30 +0800 From: Peter Chen To: Baolin Wang Cc: Alan Stern , Greg KH , stefan.koch10@gmail.com, Oliver Neukum , Muhammad Falak R Wani , Mark Brown , USB , LKML Subject: Re: [PATCH] usb: core: Add runtime resume checking Message-ID: <20160811084430.GF18967@shlinux2> References: <20160811065423.GB18967@shlinux2> <20160811081912.GE18967@shlinux2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 11, 2016 at 04:41:27PM +0800, Baolin Wang wrote: > >> >> > >> >> OK. But that is a real problem. It will pm_runtime_resume() falied > >> >> (issued in choose_wakeup()), cause usb controller has powered-off and > >> >> xHCI controller has suspended and we have no method to notify the user > >> >> to power-on USB controller. Any good suggestion to solve this, Alan > >> >> and Peter? Thanks. > >> >> > >> > > >> > Maybe you can show us the call stack why pm_runtime_resume has failed > >> > at your environment. > >> > >> OK. I try to explain it at below: > >> > >> For example: No slave attached----> usb interface runtime suspend > >> ----> usb device runtime suspend (routine is: > >> usb_suspend_device()--->generic_suspend() --> hcd_bus_suspend()--> > >> xhci_bus_suspend()) -----> xhci_ suspend() -----> power off usb > >> controller. After that if the system wants to enter suspend state, > >> then it also will issue usb_dev_suspend(), then the > >> pm_runtime_resume() function (issued in choose_wakeup() function) will > >> return -ESHUTDOWN due to xhci has been suspend and hardware is not accessible. > >> > >> We issue the pm_runtime_resume() function routine: usb_resume_device() > >> ----> generic_resume() ----> hcd_bus_resume() ---> xhci_bus_resume(), > >> but now xHCI is not accessible due to xhci_suspend() is issued and USB > >> controller is power off when no slave attached. That is why > >> pm_runtime_resume failed. > >> > > > > What host controller driver you are using? Assume you are using > > xhci-plat.c. The problem for you is this driver does not implement > > Yes. I use xhci-plat.c. > > > runtime pm operations, so the flag HCD_FLAG_HW_ACCESSIBLE is not set. > > Maybe Robert's patch is a good start for you [1] > > > > [1] http://www.spinics.net/lists/linux-usb/msg144602.html > > OK. Maybe I need to implement the runtime PM callbacks for xhci-plat, right? > I think so. -- Best Regards, Peter Chen