From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Kozlowski Subject: Re: [PATCH v10 3/5] amba: Don't unprepare the clocks if device driver wants IRQ safe runtime PM Date: Fri, 07 Nov 2014 09:01:09 +0100 Message-ID: <1415347269.8532.1.camel@AMDC1943> References: <1415263010-7992-1-git-send-email-k.kozlowski@samsung.com> <1415263010-7992-4-git-send-email-k.kozlowski@samsung.com> <3262760.d60MN56YDG@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout1.w1.samsung.com ([210.118.77.11]:53774 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751544AbaKGIBN (ORCPT ); Fri, 7 Nov 2014 03:01:13 -0500 In-reply-to: <3262760.d60MN56YDG@vostro.rjw.lan> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Rafael J. Wysocki" 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 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). Best regards, Krzysztof