Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757274Ab3HGHDS (ORCPT ); Wed, 7 Aug 2013 03:03:18 -0400 Received: from mail.active-venture.com ([67.228.131.205]:51133 "EHLO mail.active-venture.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757242Ab3HGHDQ (ORCPT ); Wed, 7 Aug 2013 03:03:16 -0400 X-Originating-IP: 108.223.40.66 Message-ID: <5201F138.3080906@roeck-us.net> Date: Wed, 07 Aug 2013 00:03:20 -0700 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623 Thunderbird/17.0.7 MIME-Version: 1.0 To: Wei Ni CC: khali@linux-fr.org, swarren@wwwdotorg.org, MLongnecker@nvidia.com, linux-arm-kernel@lists.infradead.org, lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org Subject: Re: [PATCH 1/2] hwmon: (lm90) Add power control References: <1375858358-15070-1-git-send-email-wni@nvidia.com> <1375858358-15070-2-git-send-email-wni@nvidia.com> In-Reply-To: <1375858358-15070-2-git-send-email-wni@nvidia.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4248 Lines: 131 On 08/06/2013 11:52 PM, Wei Ni wrote: > The device lm90 can be controlled by the vdd rail. > Adding the power control support to power on/off the vdd rail. > And make sure that power is enabled before accessing the device. > > Signed-off-by: Wei Ni > --- > drivers/hwmon/lm90.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 52 insertions(+) > > diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c > index cdff742..eeb0115 100644 > --- a/drivers/hwmon/lm90.c > +++ b/drivers/hwmon/lm90.c > @@ -89,6 +89,8 @@ > #include > #include > #include > +#include > +#include > > /* > * Addresses to scan > @@ -179,6 +181,8 @@ enum chips { lm90, adm1032, lm99, lm86, max6657, max6659, adt7461, max6680, > #define LM90_HAVE_TEMP3 (1 << 6) /* 3rd temperature sensor */ > #define LM90_HAVE_BROKEN_ALERT (1 << 7) /* Broken alert */ > > +#define POWER_ON_DELAY 20 /*ms*/ > + > /* > * Driver data (common to all clients) > */ > @@ -302,6 +306,7 @@ static const struct lm90_params lm90_params[] = { > struct lm90_data { > struct device *hwmon_dev; > struct mutex update_lock; > + struct regulator *lm90_reg; > char valid; /* zero until following fields are valid */ > unsigned long last_updated; /* in jiffies */ > int kind; > @@ -1391,6 +1396,48 @@ static void lm90_init_client(struct i2c_client *client) > i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1, config); > } > > +static int lm90_power_control(struct i2c_client *client, bool is_enable) > +{ > + struct lm90_data *data = i2c_get_clientdata(client); > + int ret; > + > + mutex_lock(&data->update_lock); > + > + if (!data->lm90_reg) { > + data->lm90_reg = regulator_get(&client->dev, "vdd"); > + if (IS_ERR_OR_NULL(data->lm90_reg)) { > + if (PTR_ERR(data->lm90_reg) == -ENODEV) > + dev_info(&client->dev, > + "No regulator found for vdd. Assuming vdd is always powered."); > + else > + dev_warn(&client->dev, > + "Error [%ld] in getting the regulator handle for vdd.\n", > + PTR_ERR(data->lm90_reg)); > + data->lm90_reg = NULL; > + mutex_unlock(&data->update_lock); > + return -ENODEV; I don't think it is acceptable to have the driver fail on pretty much all PCs. Also, I dislike that - even if the calling code doesn't fail - the above message would be displayed on unload as well. In general, the 'unload' flag seems unnecessary. You could just call if (data->lm90_reg) regulator_disable(); in the remove function. In addition to that, shouldn't you call regulator_put() on exit ? Also, I am missing error handling in the probe function; if something else fails, the regulator is neither disabled nor released. Guenter > + } > + } > + if (is_enable) { > + ret = regulator_enable(data->lm90_reg); > + msleep(POWER_ON_DELAY); > + } else { > + ret = regulator_disable(data->lm90_reg); > + } > + > + if (ret < 0) > + dev_err(&client->dev, > + "Error in %s rail vdd, error %d\n", > + (is_enable) ? "enabling" : "disabling", ret); > + else > + dev_info(&client->dev, "success in %s rail vdd\n", > + (is_enable) ? "enabling" : "disabling"); > + > + mutex_unlock(&data->update_lock); > + > + return ret; > +} > + > static int lm90_probe(struct i2c_client *client, > const struct i2c_device_id *id) > { > @@ -1406,6 +1453,10 @@ static int lm90_probe(struct i2c_client *client, > i2c_set_clientdata(client, data); > mutex_init(&data->update_lock); > > + err = lm90_power_control(client, true); > + if (err < 0) > + return err; > + > /* Set the device type */ > data->kind = id->driver_data; > if (data->kind == adm1032) { > @@ -1483,6 +1534,7 @@ static int lm90_remove(struct i2c_client *client) > hwmon_device_unregister(data->hwmon_dev); > lm90_remove_files(client, data); > lm90_restore_conf(client, data); > + lm90_power_control(client, false); > > return 0; > } > -- 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/