Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751585AbdITI7t (ORCPT ); Wed, 20 Sep 2017 04:59:49 -0400 Received: from mail-yw0-f172.google.com ([209.85.161.172]:50237 "EHLO mail-yw0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751009AbdITI7m (ORCPT ); Wed, 20 Sep 2017 04:59:42 -0400 X-Google-Smtp-Source: AOwi7QCNkPp++AXZttoSw/yaB7gV62Bj7jI8yQON0UNlVcgnRG6qoQ4RVzi0n9aolsTyby1qPf41x9ch+A0vJbUpU6U= MIME-Version: 1.0 In-Reply-To: <20170920084519.asyfjxo6upt36woz@valkosipuli.retiisi.org.uk> 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> From: Tomasz Figa Date: Wed, 20 Sep 2017 17:59:18 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 3/3] eeprom: at24: enable runtime pm support To: "sakari.ailus@iki.fi" 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 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 v8K8xsLg010227 Content-Length: 5641 Lines: 153 On Wed, Sep 20, 2017 at 5:45 PM, sakari.ailus@iki.fi wrote: > Hi Tomasz, > > On Wed, Sep 20, 2017 at 12:56:09PM +0900, Tomasz Figa wrote: >> Thanks Raj. >> >> Let me post my comments inline. >> >> On Wed, Sep 20, 2017 at 12:52 PM, Mani, Rajmohan >> wrote: >> > Adding Tomasz... >> > >> >> -----Original Message----- >> >> From: Mohandass, Divagar >> >> Sent: Monday, September 04, 2017 3:29 AM >> >> To: robh+dt@kernel.org; mark.rutland@arm.com; wsa@the-dreams.de; >> >> sakari.ailus@iki.fi >> >> Cc: devicetree@vger.kernel.org; linux-i2c@vger.kernel.org; linux- >> >> kernel@vger.kernel.org; Mani, Rajmohan ; >> >> Mohandass, Divagar >> >> Subject: [PATCH v6 3/3] eeprom: at24: enable runtime pm support >> >> >> >> Currently the device is kept in D0, there is an opportunity to save power by >> >> enabling runtime pm. >> >> >> >> Device can be daisy chained from PMIC and we can't rely on I2C core for auto >> >> resume/suspend. Driver will decide when to resume/suspend. >> >> >> >> Signed-off-by: Divagar Mohandass >> >> --- >> >> drivers/misc/eeprom/at24.c | 38 >> >> ++++++++++++++++++++++++++++++++++++++ >> >> 1 file changed, 38 insertions(+) >> >> >> >> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index >> >> 2199c42..d718a7a 100644 >> >> --- a/drivers/misc/eeprom/at24.c >> >> +++ b/drivers/misc/eeprom/at24.c >> >> @@ -24,6 +24,7 @@ >> >> #include >> >> #include >> >> #include >> >> +#include >> >> >> >> /* >> >> * I2C EEPROMs from most vendors are inexpensive and mostly >> >> interchangeable. >> >> @@ -501,11 +502,21 @@ static ssize_t at24_eeprom_write_i2c(struct >> >> at24_data *at24, const char *buf, static int at24_read(void *priv, unsigned int >> >> off, void *val, size_t count) { >> >> struct at24_data *at24 = priv; >> >> + struct i2c_client *client; >> >> char *buf = val; >> >> + int ret; >> >> >> >> if (unlikely(!count)) >> >> return count; >> >> >> >> + client = at24_translate_offset(at24, &off); >> >> + >> >> + ret = pm_runtime_get_sync(&client->dev); >> >> + if (ret < 0) { >> >> + pm_runtime_put_noidle(&client->dev); >> >> + return ret; >> >> + } >> >> + >> >> /* >> >> * Read data from chip, protecting against concurrent updates >> >> * from this host, but not from other I2C masters. >> >> @@ -518,6 +529,7 @@ static int at24_read(void *priv, unsigned int off, void >> >> *val, size_t count) >> >> status = at24->read_func(at24, buf, off, count); >> >> if (status < 0) { >> >> mutex_unlock(&at24->lock); >> >> + pm_runtime_put(&client->dev); >> >> return status; >> >> } >> >> buf += status; >> >> @@ -527,17 +539,29 @@ static int at24_read(void *priv, unsigned int off, void >> >> *val, size_t count) >> >> >> >> mutex_unlock(&at24->lock); >> >> >> >> + pm_runtime_put(&client->dev); >> >> + >> >> return 0; >> >> } >> >> >> >> static int at24_write(void *priv, unsigned int off, void *val, size_t count) { >> >> struct at24_data *at24 = priv; >> >> + struct i2c_client *client; >> >> char *buf = val; >> >> + int ret; >> >> >> >> if (unlikely(!count)) >> >> return -EINVAL; >> >> >> >> + client = at24_translate_offset(at24, &off); >> >> + >> >> + ret = pm_runtime_get_sync(&client->dev); >> >> + if (ret < 0) { >> >> + pm_runtime_put_noidle(&client->dev); >> >> + return ret; >> >> + } >> >> + >> >> /* >> >> * Write data to chip, protecting against concurrent updates >> >> * from this host, but not from other I2C masters. >> >> @@ -550,6 +574,7 @@ static int at24_write(void *priv, unsigned int off, void >> >> *val, size_t count) >> >> status = at24->write_func(at24, buf, off, count); >> >> if (status < 0) { >> >> mutex_unlock(&at24->lock); >> >> + pm_runtime_put(&client->dev); >> >> return status; >> >> } >> >> buf += status; >> >> @@ -559,6 +584,8 @@ static int at24_write(void *priv, unsigned int off, void >> >> *val, size_t count) >> >> >> >> mutex_unlock(&at24->lock); >> >> >> >> + pm_runtime_put(&client->dev); >> >> + >> >> return 0; >> >> } >> >> >> >> @@ -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? Bets regards, Tomasz