From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758485AbdACMZd (ORCPT ); Tue, 3 Jan 2017 07:25:33 -0500 Received: from mail-wm0-f52.google.com ([74.125.82.52]:37501 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758456AbdACMZW (ORCPT ); Tue, 3 Jan 2017 07:25:22 -0500 Date: Tue, 3 Jan 2017 12:29:03 +0000 From: Lee Jones To: Lukas Wunner Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Shevchenko , Mika Westerberg , "Rafael J . Wysocki" , Chen Yu Subject: Re: [PATCH v3] mfd: intel-lpss: Avoid resuming runtime-suspended lpss unnecessarily Message-ID: <20170103122903.GE2977@dell> References: <1475125286-12167-1-git-send-email-yu.c.chen@intel.com> <20161216231942.GA12460@wunner.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20161216231942.GA12460@wunner.de> 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 Sat, 17 Dec 2016, Lukas Wunner wrote: > you wrote on Oct 4 that you applied the below patch for v4.10. > However I don't see the patch on your for-mfd-next branch. > Maybe the patch slipped between the cracks, please double-check. > I would like to use the DPM_DIRECT_COMPLETE macro introduced by it > in a patch of my own. Chen asked me to remove the patch. > I also don't see a pull from you in Linus' tree yet. Please note > that this merge window will be shorter than usual and pulls should > be sent out before coming Friday. Right, I was on vacation. All sorted now. > On Thu, Sep 29, 2016 at 01:01:26PM +0800, 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 > > --- > > 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 */ -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog