Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965233Ab3HHLXD (ORCPT ); Thu, 8 Aug 2013 07:23:03 -0400 Received: from mail.active-venture.com ([67.228.131.205]:60519 "EHLO mail.active-venture.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757762Ab3HHLXA (ORCPT ); Thu, 8 Aug 2013 07:23:00 -0400 X-Originating-IP: 108.223.40.66 Message-ID: <52037F9A.7070802@roeck-us.net> Date: Thu, 08 Aug 2013 04:23:06 -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" , Matthew Longnecker , "linux-arm-kernel@lists.infradead.org" , "lm-sensors@lm-sensors.org" , "linux-kernel@vger.kernel.org" , "linux-tegra@vger.kernel.org" Subject: Re: [PATCH v2 1/3] hwmon: (lm90) Add power control References: <1375944991-29182-1-git-send-email-wni@nvidia.com> <1375944991-29182-2-git-send-email-wni@nvidia.com> <520359E9.1000600@roeck-us.net> <52036920.4050808@nvidia.com> In-Reply-To: <52036920.4050808@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: 6093 Lines: 194 On 08/08/2013 02:47 AM, Wei Ni wrote: > On 08/08/2013 04:42 PM, Guenter Roeck wrote: >> On 08/07/2013 11:56 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 | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ >>> 1 file changed, 49 insertions(+) >>> >>> diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c >>> index cdff742..306a348 100644 >>> --- a/drivers/hwmon/lm90.c >>> +++ b/drivers/hwmon/lm90.c >>> @@ -89,6 +89,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> >>> /* >>> * Addresses to scan >>> @@ -302,6 +303,7 @@ 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 +1393,32 @@ static void lm90_init_client(struct i2c_client *client) >>> i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1, config); >>> } >>> >>> +static void lm90_power_control(struct i2c_client *client, bool is_enable) >>> +{ >>> + struct lm90_data *data = i2c_get_clientdata(client); >>> + int ret; >>> + >>> + if (!data->lm90_reg) >>> + return; >>> + >>> + mutex_lock(&data->update_lock); >>> + >> >> This is only called during probe and remove, so the mutex is unnecessary. > > I considered that we may call this function in suspend/resume routine, > so I add this mutex. > But as you said, currently we doesn't have these routine yet, the mutex > is unnecessary, so I will remove it. > In that case, you can call mutex_lock() regulator_enable() / regulator_disable() mutex_unlock() directly in those functions. Again no need for the additional function. >> >>> + if (is_enable) >>> + ret = regulator_enable(data->lm90_reg); >>> + 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"); >>> + >> which reduces the function to (pretty much unnecessary) messages and an if statement >> which you only need because you have the function. >> >> You should just call regulator_enable in probe and regulator_disable in remove. > > Ok, I will remove these messages and this function. > >> >> Guenter >> >>> + mutex_unlock(&data->update_lock); >>> +} >>> + >>> static int lm90_probe(struct i2c_client *client, >>> const struct i2c_device_id *id) >>> { >>> @@ -1406,6 +1434,20 @@ static int lm90_probe(struct i2c_client *client, >>> i2c_set_clientdata(client, data); >>> mutex_init(&data->update_lock); >>> >>> + data->lm90_reg = regulator_get(&client->dev, "vdd"); >> >> You should use devm_regulator_get(). Then you also don't need the call to regulator_put(). > > Oh, yes, you are right, I will do it. > >> >>> + if (IS_ERR_OR_NULL(data->lm90_reg)) { >> >> The function never returns NULL except if the regulator subsystem is not configured, >> so IS_ERR() is more appropriate. >> >> If the regulator subsystem is not configured, you especially don't need or want >> to pollute the log with an error message. >> >>> + 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)); >> >> I consider the messages unnecessary and confusing. You are polluting the log >> of pretty much every PC user who has one of the supported chips in the system, >> and of everyone else not using regulators for this chip. > > Ok, I will remove these codes. > So I will write something like: > if (!IS_ERR(data->lm90_reg)) { > ret = regulator_enable(data->lm90_reg); > if (ret < 0) { > dev_err(); > return ret; > } > } else { Handle the error in the if case. > if (PTR_ERR(data->lm90_reg) == -EPROBE_DEFER) > return -EPRPBE_DEFER; > > data->lm90_reg = !!IS_ERR(data->lm90_reg); You know that IS_ERR is true here. Unless I am missing something, this would assign "1" to lm90_reg. > } > >> >>> + data->lm90_reg = NULL; >> >> As pointed out, this is unnecessary, and you should handle -EPROBE_DEFER correctly. > > I think get_regulator() will return error values, not only > -EPROBE_DEFER, so we should set data->lm90_reg to NULL to handle other > error values. > Matter of opinion if you want to check for IS_ERR or NULL later on. >> >>> + } >>> + >>> + lm90_power_control(client, true); >>> + >>> /* Set the device type */ >>> data->kind = id->driver_data; >>> if (data->kind == adm1032) { >>> @@ -1473,6 +1515,10 @@ exit_remove_files: >>> lm90_remove_files(client, data); >>> exit_restore: >>> lm90_restore_conf(client, data); >>> + lm90_power_control(client, false); >>> + if (data->lm90_reg) >>> + regulator_put(data->lm90_reg); >>> + >>> return err; >>> } >>> >>> @@ -1483,6 +1529,9 @@ 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); >>> + if (data->lm90_reg) >>> + regulator_put(data->lm90_reg); >>> >>> 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/