From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753737AbcJDOxO (ORCPT ); Tue, 4 Oct 2016 10:53:14 -0400 Received: from mail-wm0-f51.google.com ([74.125.82.51]:34429 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752918AbcJDOxM (ORCPT ); Tue, 4 Oct 2016 10:53:12 -0400 Date: Tue, 4 Oct 2016 15:55:28 +0100 From: Lee Jones To: "Rafael J. Wysocki" Cc: Chen Yu , Linux PM , Pavel Machek , Len Brown , Linux Kernel Mailing List , Andy Shevchenko , Mika Westerberg , "Rafael J . Wysocki" Subject: Re: [PATCH][v3] mfd: intel-lpss: Avoid resuming runtime-suspended lpss unnecessarily Message-ID: <20161004145528.GE29257@dell> References: <1475125286-12167-1-git-send-email-yu.c.chen@intel.com> <20160930002943.GC13971@dell> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 30 Sep 2016, Rafael J. Wysocki wrote: > On Fri, Sep 30, 2016 at 2:29 AM, Lee Jones wrote: > > On Fri, 30 Sep 2016, Rafael J. Wysocki wrote: > > > >> Hi Lee, > >> > >> On Thu, Sep 29, 2016 at 7:01 AM, Chen Yu wrote: > >> > We have report that the intel_lpss_prepare() takes too much time during > >> > suspend, and this is because we first resume the devices from runtime > >> > suspend by resume_lpss_device(), to make sure they are in proper state > >> > before system suspend, which takes 100ms for each LPSS devices(PCI power > >> > state from D3_cold to D0). And since resume_lpss_device() resumes the > >> > devices synchronously, we might get huge latency if we have many > >> > LPSS devices. > >> > > >> > So first try is to use pm_request_resume() instead, to make the runtime > >> > resume process asynchronously. Unfortunately the asynchronous runtime > >> > resume relies on pm_wq, which is freezed at early stage. So we choose > >> > another method, that is to avoid resuming runtime-suspended devices, > >> > if they are already runtime suspended. This is safe because for LPSS > >> > driver, the runtime suspend and system suspend are of the same > >> > hook - i.e., intel_lpss_suspend(). And moreover, this device is > >> > neither runtime wakeup source nor system wakeup source. > >> > > >> > Suggested-by: Rafael J. Wysocki > >> > Acked-by: Mika Westerberg > >> > Reviewed-by: Andy Shevchenko > >> > Cc: Andy Shevchenko > >> > Cc: Mika Westerberg > >> > Cc: Rafael J. Wysocki > >> > Cc: Lee Jones > >> > Signed-off-by: Chen Yu > >> > >> If this is fine with you and you'd like to apply it, please feel free > >> to add my ACK to it. > >> > >> Alternatively, if you'd prefer me to apply it, please let me know. > > > > You want this in for v3.9? > > I'd rather queue it up for 4.10 (assuming that the above and below > major version numbers are simply off by one by mistake). Yes, of course they are off by one. This is what happens when you conduct mail duties with jetlag. :) > > I just started applying patches for v3.10. > > > > If you're certain there are 0% chance of regressions, I will still > > apply this for v3.9 with your Ack. > > 4.10 should be fine. Great. > >> > --- > >> > drivers/mfd/intel-lpss.c | 9 +++++++++ > >> > include/linux/pm.h | 7 +++++++ > >> > 2 files changed, 16 insertions(+) > >> > > >> > diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c > >> > index 41b1138..2583db8 100644 > >> > --- a/drivers/mfd/intel-lpss.c > >> > +++ b/drivers/mfd/intel-lpss.c > >> > @@ -485,6 +485,15 @@ static int resume_lpss_device(struct device *dev, void *data) > >> > int intel_lpss_prepare(struct device *dev) > >> > { > >> > /* > >> > + * This is safe because: > >> > + * 1. The runtime suspend and system suspend > >> > + * are of the same hook. > >> > + * 2. This device is neither runtime wakeup source > >> > + * nor system wakeup source. > >> > + */ > >> > + if (pm_runtime_status_suspended(dev)) > >> > + return DPM_DIRECT_COMPLETE; > >> > + /* > >> > * Resume both child devices before entering system sleep. This > >> > * ensures that they are in proper state before they get suspended. > >> > */ > >> > diff --git a/include/linux/pm.h b/include/linux/pm.h > >> > index 06eb353..4a788b4 100644 > >> > --- a/include/linux/pm.h > >> > +++ b/include/linux/pm.h > >> > @@ -786,4 +786,11 @@ enum dpm_order { > >> > DPM_ORDER_DEV_LAST, > >> > }; > >> > > >> > +/* > >> > + * Return this from system suspend/hibernation ->prepare() callback to > >> > + * request the core to leave the device runtime-suspended during system > >> > + * suspend if possible. > >> > + */ > >> > +#define DPM_DIRECT_COMPLETE 1 > >> > + > >> > #endif /* _LINUX_PM_H */ > >> > -- > > Thanks, > Rafael -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog