Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753104AbaKGXbv (ORCPT ); Fri, 7 Nov 2014 18:31:51 -0500 Received: from v094114.home.net.pl ([79.96.170.134]:53103 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751965AbaKGXbt (ORCPT ); Fri, 7 Nov 2014 18:31:49 -0500 From: "Rafael J. Wysocki" To: Krzysztof Kozlowski Cc: Len Brown , Pavel Machek , Russell King , Dan Williams , Vinod Koul , Ulf Hansson , Alan Stern , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, Lars-Peter Clausen , Michal Simek , Kevin Hilman , Laurent Pinchart , Kyungmin Park , Marek Szyprowski , Bartlomiej Zolnierkiewicz Subject: Re: [PATCH v10 3/5] amba: Don't unprepare the clocks if device driver wants IRQ safe runtime PM Date: Sat, 08 Nov 2014 00:52:38 +0100 Message-ID: <1582300.GC6cj61ZAD@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.16.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1415347269.8532.1.camel@AMDC1943> References: <1415263010-7992-1-git-send-email-k.kozlowski@samsung.com> <3262760.d60MN56YDG@vostro.rjw.lan> <1415347269.8532.1.camel@AMDC1943> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit 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 Friday, November 07, 2014 09:01:09 AM Krzysztof Kozlowski wrote: > On czw, 2014-11-06 at 23:52 +0100, Rafael J. Wysocki wrote: > > On Thursday, November 06, 2014 09:36:48 AM Krzysztof Kozlowski wrote: > > > The AMBA bus driver defines runtime Power Management functions which > > > disable and unprepare AMBA bus clock. This is problematic for runtime PM > > > because unpreparing a clock might sleep so it is not interrupt safe. > > > > > > However some drivers may want to implement runtime PM functions in > > > interrupt-safe way (see pm_runtime_irq_safe()). In such case the AMBA > > > bus driver should only disable/enable the clock in runtime suspend and > > > resume callbacks. > > > > > > Detect the device driver behavior during runtime suspend. During runtime > > > resume deal with clocks according to stored value. > > > > > > Signed-off-by: Krzysztof Kozlowski > > > --- > > > drivers/amba/bus.c | 17 +++++++++++++---- > > > include/linux/amba/bus.h | 1 + > > > 2 files changed, 14 insertions(+), 4 deletions(-) > > > > > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > > > index 47bbdc1b5be3..356f906c6966 100644 > > > --- a/drivers/amba/bus.c > > > +++ b/drivers/amba/bus.c > > > @@ -95,8 +95,14 @@ static int amba_pm_runtime_suspend(struct device *dev) > > > struct amba_device *pcdev = to_amba_device(dev); > > > int ret = pm_generic_runtime_suspend(dev); > > > > > > - if (ret == 0 && dev->driver) > > > - clk_disable_unprepare(pcdev->pclk); > > > + if (ret == 0 && dev->driver) { > > > + pcdev->irq_safe = dev->power.irq_safe; > > > + > > > + if (pcdev->irq_safe) > > > + clk_disable(pcdev->pclk); > > > + else > > > + clk_disable_unprepare(pcdev->pclk); > > > + } > > > > > > return ret; > > > } > > > @@ -107,7 +113,10 @@ static int amba_pm_runtime_resume(struct device *dev) > > > int ret; > > > > > > if (dev->driver) { > > > - ret = clk_prepare_enable(pcdev->pclk); > > > + if (pcdev->irq_safe) > > > + ret = clk_enable(pcdev->pclk); > > > + else > > > + ret = clk_prepare_enable(pcdev->pclk); > > > /* Failure is probably fatal to the system, but... */ > > > if (ret) > > > return ret; > > > @@ -115,7 +124,7 @@ static int amba_pm_runtime_resume(struct device *dev) > > > > > > return pm_generic_runtime_resume(dev); > > > } > > > -#endif > > > +#endif /* CONFIG_PM */ > > > > > > static const struct dev_pm_ops amba_pm = { > > > .suspend = pm_generic_suspend, > > > diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h > > > index ac02f9bd63dc..c4bae79851fb 100644 > > > --- a/include/linux/amba/bus.h > > > +++ b/include/linux/amba/bus.h > > > @@ -32,6 +32,7 @@ struct amba_device { > > > struct clk *pclk; > > > unsigned int periphid; > > > unsigned int irq[AMBA_NR_IRQS]; > > > + unsigned int irq_safe:1; > > > > Why do we need the new flag? Seems redundant to me. > > Some poorly written driver could set irq_safe somewhere between suspend > and resume (e.g. in suspend callback). It could also modify your bus type irq_safe flag to hide the fact. In my opinion, it doesn't really help. Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/