From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754205AbaKEItF (ORCPT ); Wed, 5 Nov 2014 03:49:05 -0500 Received: from mailout1.w1.samsung.com ([210.118.77.11]:21641 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751298AbaKEItA (ORCPT ); Wed, 5 Nov 2014 03:49:00 -0500 X-AuditID: cbfec7f4-b7f6c6d00000120b-33-5459e4794291 Message-id: <1415177336.15850.14.camel@AMDC1943> Subject: Re: [PATCH v9 2/4] amba: Don't unprepare the clocks if device driver wants IRQ safe runtime PM From: Krzysztof Kozlowski To: Ulf Hansson Cc: "Rafael J. Wysocki" , Len Brown , Pavel Machek , Jonathan Corbet , 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 Date: Wed, 05 Nov 2014 09:48:56 +0100 In-reply-to: References: <1415105570-7871-1-git-send-email-k.kozlowski@samsung.com> <1415105570-7871-3-git-send-email-k.kozlowski@samsung.com> Content-type: text/plain; charset=UTF-8 X-Mailer: Evolution 3.10.4-0ubuntu2 MIME-version: 1.0 Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprPIsWRmVeSWpSXmKPExsVy+t/xy7qVTyJDDOa+tLbYOGM9q8WTA+2M FtOnXmC0WD31L6vF082PmSzONr1ht1gyeT6rRefEJewWs6bsZbK4vGsOm8Xn3iOMFrcv81qs PXKX3eLdywiLu6eOslmcOX2J1WLC7wtsFsfXhlu87NvP4iDs0dLcw+Yxu2Mmq8fiPS+ZPDat 6mTzuHNtD5vH4r7JrB5L3hxi9dhytZ3FY/bdH4wefVtWMXqsWP2d3ePzJjmPvZ9/swTwRnHZ pKTmZJalFunbJXBlrJ8xh6VgvXDFhFOzWRoYr/B3MXJySAiYSJzetJINwhaTuHBvPZDNxSEk sJRRYsLsCVDOZ0aJxWv6wap4BQwkeo6sYgGxhQUyJVqOn2AHsdkEjCU2L18CViMioCGx5+F5 VpBmZoEWNon7X3cygyRYBFQl3l24AtTMwcEpECzR+IARYsEpRomDPSeYQGqYBdQlJs1bxAxS IyGgLNHY7waxV1Dix+R7LBAl8hKb17xlnsAoMAtJxywkZbOQlC1gZF7FKJpamlxQnJSea6hX nJhbXJqXrpecn7uJERKpX3YwLj5mdYhRgINRiYfXoykyRIg1say4MvcQowQHs5IIL+cloBBv SmJlVWpRfnxRaU5q8SFGJg5OqQbGRSkHO5g6Y95vnXXBJ7RC5GFt7MqCmDMBv9U/W/7b/UKN v2HTN59Dp10erC0vcJ9+p6virNn8pH9du2ze39podSw1vrqx4oKPtHv5w5QPqhEPxN7v7ag9 uiW4+efnzyuNXPep6p534NGqnrfDQGmXt32H5YH/bEzZ17lWyjZc3Z3Nr3Tzz6yLSizFGYmG WsxFxYkAxUFTJrICAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On wto, 2014-11-04 at 20:06 +0100, Ulf Hansson wrote: > On 4 November 2014 13:52, 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 | 24 ++++++++++++++++++++---- > > include/linux/amba/bus.h | 1 + > > 2 files changed, 21 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > > index 47bbdc1b5be3..27ec8882ec8e 100644 > > --- a/drivers/amba/bus.c > > +++ b/drivers/amba/bus.c > > @@ -85,6 +85,13 @@ static struct device_attribute amba_dev_attrs[] = { > > }; > > > > #ifdef CONFIG_PM > > + > > +#ifdef CONFIG_PM_RUNTIME > > +#define get_pm_runtime_irq_safe(dev) ((dev)->power.irq_safe) > > +#else > > +#define get_pm_runtime_irq_safe(dev) 1 > > No, this doesn't work for those drivers that isn't configured as > irq_safe. The pm_runtime_force_suspend() invoked from the driver's > system PM suspend callback, will expect clocks to be unprepared when > CONFIG_PM_RUNTIME is unset. D'oh! You're right... > To address this issue, in principle we need to know whether the driver > has invoked pm_runtime_irq_safe(), even when CONFIG_PM_RUNTIME is > unset. > > This may be solved by the help of PM core: > 1) Move the irq_safe member in the struct dev_pm_info, outside the > #ifdef CONFIG_PM_RUNTIME. > 2) Let the pm_runtime_irq_safe() function be implemented for CONFIG_PM > instead of CONFIG_PM_RUNTIME. Before I'll start implementing this - could PM maintainers share their opinion on such change? Best regards, Krzysztof > If the PM core maintainers don't like that approach we can always add > an amba specific wrapper function for pm_runtime_irq_safe() and store > the information needed in the struct amba_device. > > Kind regards > Uffe