From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935294AbcI3AbO (ORCPT ); Thu, 29 Sep 2016 20:31:14 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:36118 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754345AbcI3AbG (ORCPT ); Thu, 29 Sep 2016 20:31:06 -0400 MIME-Version: 1.0 In-Reply-To: <20160930002943.GC13971@dell> References: <1475125286-12167-1-git-send-email-yu.c.chen@intel.com> <20160930002943.GC13971@dell> From: "Rafael J. Wysocki" Date: Fri, 30 Sep 2016 02:31:03 +0200 X-Google-Sender-Auth: SMo3xHT6p-qScNfzqCNhoCKmJEM Message-ID: Subject: Re: [PATCH][v3] mfd: intel-lpss: Avoid resuming runtime-suspended lpss unnecessarily To: Lee Jones Cc: "Rafael J. Wysocki" , Chen Yu , Linux PM , Pavel Machek , Len Brown , Linux Kernel Mailing List , Andy Shevchenko , Mika Westerberg , "Rafael J . Wysocki" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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). > 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. >> > --- >> > 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