From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756095AbdJJD4M (ORCPT ); Mon, 9 Oct 2017 23:56:12 -0400 Received: from mail-qt0-f179.google.com ([209.85.216.179]:56154 "EHLO mail-qt0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755961AbdJJD4J (ORCPT ); Mon, 9 Oct 2017 23:56:09 -0400 X-Google-Smtp-Source: AOwi7QDMlcUVB2e+hF5mNS9QKfao5N0mb2yHFTg3GUwUNBbQ1bsaCUn+tENjxWt9j9lBNvGbZGwG7vXaBTykx2bPdSI= MIME-Version: 1.0 In-Reply-To: <7B8CE47BD58441468D2BB13285B50E6031DF530B@BGSMSX107.gar.corp.intel.com> References: <1504520928-5191-1-git-send-email-divagar.mohandass@intel.com> <1504520928-5191-4-git-send-email-divagar.mohandass@intel.com> <6F87890CF0F5204F892DEA1EF0D77A5972FC1278@FMSMSX114.amr.corp.intel.com> <20170920084519.asyfjxo6upt36woz@valkosipuli.retiisi.org.uk> <20170920093222.yzfw2ctrupep5iqx@valkosipuli.retiisi.org.uk> <20171003135109.v7ch7oc4fvjwzl7w@valkosipuli.retiisi.org.uk> <7B8CE47BD58441468D2BB13285B50E6031DF530B@BGSMSX107.gar.corp.intel.com> From: Tomasz Figa Date: Tue, 10 Oct 2017 12:55:45 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 3/3] eeprom: at24: enable runtime pm support To: "Mohandass, Divagar" Cc: "sakari.ailus@iki.fi" , "Mani, Rajmohan" , "robh+dt@kernel.org" , "mark.rutland@arm.com" , "wsa@the-dreams.de" , "devicetree@vger.kernel.org" , "linux-i2c@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "mika.westerberg@linux.intel.com" , "linux-pm@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v9A3uGpW009557 On Mon, Oct 9, 2017 at 12:14 PM, Mohandass, Divagar wrote: > Hi Tomasz, > >>-----Original Message----- >>From: sakari.ailus@iki.fi [mailto:sakari.ailus@iki.fi] >>Sent: Tuesday, October 03, 2017 7:21 PM >>To: Tomasz Figa >>Cc: Mani, Rajmohan ; Mohandass, Divagar >>; robh+dt@kernel.org; >>mark.rutland@arm.com; wsa@the-dreams.de; devicetree@vger.kernel.org; >>linux-i2c@vger.kernel.org; linux-kernel@vger.kernel.org; >>mika.westerberg@linux.intel.com; linux-pm@vger.kernel.org >>Subject: Re: [PATCH v6 3/3] eeprom: at24: enable runtime pm support >> >>Hi Tomasz, >> >>On Wed, Sep 20, 2017 at 12:32:22PM +0300, sakari.ailus@iki.fi wrote: >>> > >> >> @@ -743,11 +770,17 @@ static int at24_probe(struct i2c_client >>> > >> >> *client, const struct i2c_device_id *id) >>> > >> >> >>> > >> >> i2c_set_clientdata(client, at24); >>> > >> >> >>> > >> >> + /* enable runtime pm */ >>> > >> >> + pm_runtime_get_noresume(&client->dev); >>> > >> >> + pm_runtime_set_active(&client->dev); >>> > >> >> + pm_runtime_enable(&client->dev); >>> > >> >>> > >> Do we need this get_noresume/set_active dance? I remember it was >>> > >> for some reason needed for PCI devices, but I don't see why for >>> > >> I2C anything else than just pm_runtime_enable() would be necessary. >>> > > >>> > > You specifically do not need (all) this for PCI devices, but AFAIU >>> > > for I涎 >>> > > devices you do. The runtime PM status of a device is disabled by >>> > > default and the use count is zero, but on ACPI based systems the >>> > > device is still powered on. >>> > >>> > Okay, so _get_noresume() and _set_active() would do the thing for >>> > ACPI indeed, but not sure about other platforms. Perhaps _enable(), >>> > _get_sync() would be more general? >>> >>> What I ended up doing in e.g. the smiapp driver was to explicitly >>> power the device on first and then enable runtime PM. (See >>> drivers/media/i2c/smiapp/smiapp-core.c .) This approach works even if >>> CONFIG_PM is disabled, both on DT and ACPI. >> >>pm_runtime_get_noresume() + pm_runtime_put() can be replaced by a single >>pm_runtime_idle() call (where pm_runtime_put() was). pm_runtime_enable() >>is required to enable runtime PM for a device. > > Verified the change suggested by Sakari. > Let me know I can send a updated patch version with this change. Okay, looks like Sakari confirmed that the driver should work fine without callbacks, so please go ahead. Thanks for patience. Best regards, Tomasz