Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754859Ab3ILVkU (ORCPT ); Thu, 12 Sep 2013 17:40:20 -0400 Received: from mail-wg0-f50.google.com ([74.125.82.50]:52372 "EHLO mail-wg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754144Ab3ILVkS (ORCPT ); Thu, 12 Sep 2013 17:40:18 -0400 MIME-Version: 1.0 In-Reply-To: <87vc25pvvm.fsf@linaro.org> 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> Date: Thu, 12 Sep 2013 14:40:15 -0700 Message-ID: Subject: Re: [PATCH v2 1/9] i2c: prepare runtime PM support for I2C client devices From: Kevin Hilman To: Mika Westerberg Cc: linux-i2c@vger.kernel.org, Wolfram Sang , "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, LKML , Lv Zheng , Aaron Lu , linux-arm-kernel , Mark Brown , Dmitry Torokhov , Mauro Carvalho Chehab , Samuel Ortiz , Lee Jones , Arnd Bergmann , Greg Kroah-Hartman , Liam Girdwood , Kyungmin Park Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1495 Lines: 35 On Thu, Sep 12, 2013 at 2:34 PM, Kevin Hilman wrote: > Mika Westerberg writes: > >> From: Aaron Lu >> >> This patch adds runtime PM support for the I2C bus in a similar way that >> has been done for PCI bus already. This means that the I2C bus core >> prepares runtime PM for a client device just before a driver is about to be >> bound to it. Devices that are not bound to any driver are not prepared for >> runtime PM. >> >> In order to take advantage of this runtime PM support, the client device >> driver needs drop the device runtime PM reference count by calling >> pm_runtime_put() in its ->probe() callback and possibly implement rest of >> the runtime PM callbacks. >> >> If the driver doesn't support runtime PM (like most of the existing I2C >> client drivers), the device in question is regarded as being runtime PM >> active and powered on. > > But for existing drivers which already support runtime PM (at least 7 by > a quick grep), they will be stuck runtime enabled and stop hitting > low-power states after this patch. Oops, nevermind. I was mixing this up with runtime PM on the i2c adapter but this is for the i2c client. Sorry for the noise. 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/