Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932956Ab3IMObC (ORCPT ); Fri, 13 Sep 2013 10:31:02 -0400 Received: from mail-pb0-f49.google.com ([209.85.160.49]:48405 "EHLO mail-pb0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932232Ab3IMOa7 (ORCPT ); Fri, 13 Sep 2013 10:30:59 -0400 From: Kevin Hilman To: Mika Westerberg Cc: linux-i2c@vger.kernel.org, Wolfram Sang , "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Lv Zheng , Aaron Lu , linux-arm-kernel@lists.infradead.org, Mark Brown , Dmitry Torokhov , Mauro Carvalho Chehab , Samuel Ortiz , Lee Jones , Arnd Bergmann , Greg Kroah-Hartman , Liam Girdwood , Kyungmin Park Subject: Re: [PATCH v2 1/9] i2c: prepare runtime PM support for I2C client devices References: <1378913560-2752-1-git-send-email-mika.westerberg@linux.intel.com> <1378913560-2752-2-git-send-email-mika.westerberg@linux.intel.com> <87vc25pvvm.fsf@linaro.org> <20130913065434.GZ7393@intel.com> Date: Fri, 13 Sep 2013 07:30:55 -0700 In-Reply-To: <20130913065434.GZ7393@intel.com> (Mika Westerberg's message of "Fri, 13 Sep 2013 09:54:34 +0300") Message-ID: <87bo3whjz4.fsf@linaro.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1832 Lines: 49 Mika Westerberg writes: > On Thu, Sep 12, 2013 at 02:34:21PM -0700, Kevin Hilman wrote: >> > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c >> > index f32ca29..44374b4 100644 >> > --- a/drivers/i2c/i2c-core.c >> > +++ b/drivers/i2c/i2c-core.c >> > @@ -248,11 +248,30 @@ static int i2c_device_probe(struct device *dev) >> > client->flags & I2C_CLIENT_WAKE); >> > dev_dbg(dev, "probe\n"); >> > >> > + /* Make sure the adapter is active */ >> > + pm_runtime_get_sync(&client->adapter->dev); >> > + >> > + /* >> > + * Enable runtime PM for the client device. If the client wants to >> > + * participate on runtime PM it should call pm_runtime_put() in its >> > + * probe() callback. >> > + */ >> > + pm_runtime_get_noresume(&client->dev); >> > + pm_runtime_set_active(&client->dev); >> >> Why the set_active here? >> >> For hardware that is disabled/powered-off on startup, there will now be >> a mismatch between the hardware state an the RPM core state. > > The call to pm_runtime_get_noresume() should make sure that the device is > in active state (at least in state where it can access the bus) if I'm > understanding this right. No, after _get_noresume(), nothing happens to the hardware. It simply increments the usecount. From pm_runtime.h: static inline void pm_runtime_get_noresume(struct device *dev) { atomic_inc(&dev->power.usage_count); } So after the _get_noresume() and _set_active() you're very likely to have a disconnect between the hardware state and what state RPM thinks the hardware is in. Kevin -- 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/