Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964906Ab3HHJrM (ORCPT ); Thu, 8 Aug 2013 05:47:12 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:14295 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757710Ab3HHJrK (ORCPT ); Thu, 8 Aug 2013 05:47:10 -0400 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Thu, 08 Aug 2013 02:45:25 -0700 Message-ID: <52036920.4050808@nvidia.com> Date: Thu, 8 Aug 2013 17:47:12 +0800 From: Wei Ni User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623 Thunderbird/17.0.7 MIME-Version: 1.0 To: Guenter Roeck 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> In-Reply-To: <520359E9.1000600@roeck-us.net> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5451 Lines: 175 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. > >> + 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 { if (PTR_ERR(data->lm90_reg) == -EPROBE_DEFER) return -EPRPBE_DEFER; data->lm90_reg = !!IS_ERR(data->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. > >> + } >> + >> + 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/