Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752670AbaKFKDM (ORCPT ); Thu, 6 Nov 2014 05:03:12 -0500 Received: from mail-qg0-f47.google.com ([209.85.192.47]:42456 "EHLO mail-qg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751946AbaKFKDG (ORCPT ); Thu, 6 Nov 2014 05:03:06 -0500 MIME-Version: 1.0 In-Reply-To: <1415263010-7992-4-git-send-email-k.kozlowski@samsung.com> References: <1415263010-7992-1-git-send-email-k.kozlowski@samsung.com> <1415263010-7992-4-git-send-email-k.kozlowski@samsung.com> Date: Thu, 6 Nov 2014 11:03:05 +0100 Message-ID: Subject: Re: [PATCH v10 3/5] amba: Don't unprepare the clocks if device driver wants IRQ safe runtime PM From: Ulf Hansson To: Krzysztof Kozlowski Cc: "Rafael J. Wysocki" , Len Brown , Pavel Machek , Russell King , Dan Williams , Vinod Koul , 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 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 6 November 2014 09:36, 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 Reviewed-by: Ulf Hansson > --- > 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; > }; > > struct amba_driver { > -- > 1.9.1 > -- 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/