From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753870AbdJIDOd (ORCPT ); Sun, 8 Oct 2017 23:14:33 -0400 Received: from mga11.intel.com ([192.55.52.93]:54567 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752161AbdJIDOb (ORCPT ); Sun, 8 Oct 2017 23:14:31 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.42,498,1500966000"; d="scan'208";a="144235824" From: "Mohandass, Divagar" To: "'sakari.ailus@iki.fi'" , Tomasz Figa CC: "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" Subject: RE: [PATCH v6 3/3] eeprom: at24: enable runtime pm support Thread-Topic: [PATCH v6 3/3] eeprom: at24: enable runtime pm support Thread-Index: AQHTJWiHSjUrnL9UXU+AIW3QOhavW6K84NqAgAAA6oCAAFDMAIAAA+cAgAAJPQCAFLacgIABnbAQ Date: Mon, 9 Oct 2017 03:14:24 +0000 Message-ID: <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> In-Reply-To: <20171003135109.v7ch7oc4fvjwzl7w@valkosipuli.retiisi.org.uk> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-version: 11.0.0.116 dlp-reaction: no-action x-originating-ip: [10.223.10.10] Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 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 base64 to 8bit by nfs id v993EfVe006006 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. > >pm_runtime_allow() may be omitted but then to make the runtime PM >framework to make the power state transitions this needs to be configured >from the user space --- which I don't think is intended. > >Cc linux-pm, too. > >-- >Regards, > >Sakari Ailus >e-mail: sakari.ailus@iki.fi