[v2,3/3] eeprom: at24: enable runtime pm support

Message ID 1502736119-32084-4-git-send-email-divagar.mohandass@intel.com
State Superseded
Headers show

Commit Message

Divagar Mohandass Aug. 14, 2017, 6:41 p.m.
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 <divagar.mohandass@intel.com>
---
 drivers/misc/eeprom/at24.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

Comments

Sakari Ailus Aug. 22, 2017, 8:55 a.m. | #1
Hi Divagar,

Thanks for the patch. Please see my comments below.

On Tue, Aug 15, 2017 at 12:11:59AM +0530, Divagar Mohandass wrote:
> 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 <divagar.mohandass@intel.com>
> ---
>  drivers/misc/eeprom/at24.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index 2199c42..0d26681 100644
> --- a/drivers/misc/eeprom/at24.c
> +++ b/drivers/misc/eeprom/at24.c
> @@ -24,6 +24,7 @@
>  #include <linux/i2c.h>
>  #include <linux/nvmem-provider.h>
>  #include <linux/platform_data/at24.h>
> +#include <linux/pm_runtime.h>
>  
>  /*
>   * 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;
> +	}
> +

at24_read() may fail between the two chunks here. You'll need
pm_runtime_put() before returning the error code.

>  	/*
>  	 * Read data from chip, protecting against concurrent updates
>  	 * from this host, but not from other I2C masters.
> @@ -527,17 +538,29 @@ 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.

Ditto for write.

> @@ -559,6 +582,8 @@ 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;
>  }
>  
> @@ -743,6 +768,13 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  
>  	i2c_set_clientdata(client, at24);
>  
> +	/* enable runtime pm */
> +	err = pm_runtime_set_active(&client->dev);
> +	if (err < 0)
> +		goto err_clients;
> +
> +	pm_runtime_enable(&client->dev);
> +

Here, too: at24_read() below can fail, as well as nvmem_register().

>  	/*
>  	 * Perform a one-byte test read to verify that the
>  	 * chip is functional.
> @@ -810,6 +842,8 @@ static int at24_remove(struct i2c_client *client)
>  	for (i = 1; i < at24->num_addresses; i++)
>  		i2c_unregister_device(at24->client[i]);
>  
> +	pm_runtime_disable(&client->dev);

pm_runtime_set_suspended(&client->dev)

> +
>  	return 0;
>  }
>
Divagar Mohandass Aug. 30, 2017, 4:05 a.m. | #2
Hi Sakari,

Thanks for your review comments.
My comments below.

---
^Divagar

>-----Original Message-----
>From: Sakari Ailus [mailto:sakari.ailus@iki.fi]
>Sent: Tuesday, August 22, 2017 2:26 PM
>To: Mohandass, Divagar <divagar.mohandass@intel.com>
>Cc: 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; Mani, Rajmohan <rajmohan.mani@intel.com>
>Subject: Re: [PATCH v2 3/3] eeprom: at24: enable runtime pm support
>
>Hi Divagar,
>
>Thanks for the patch. Please see my comments below.
>
>On Tue, Aug 15, 2017 at 12:11:59AM +0530, Divagar Mohandass wrote:
>> 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 <divagar.mohandass@intel.com>
>> ---
>>  drivers/misc/eeprom/at24.c | 34 ++++++++++++++++++++++++++++++++++
>>  1 file changed, 34 insertions(+)
>>
>> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
>> index 2199c42..0d26681 100644
>> --- a/drivers/misc/eeprom/at24.c
>> +++ b/drivers/misc/eeprom/at24.c
>> @@ -24,6 +24,7 @@
>>  #include <linux/i2c.h>
>>  #include <linux/nvmem-provider.h>
>>  #include <linux/platform_data/at24.h>
>> +#include <linux/pm_runtime.h>
>>
>>  /*
>>   * 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;
>> +	}
>> +
>
>at24_read() may fail between the two chunks here. You'll need
>pm_runtime_put() before returning the error code.

Ack

>
>>  	/*
>>  	 * Read data from chip, protecting against concurrent updates
>>  	 * from this host, but not from other I2C masters.
>> @@ -527,17 +538,29 @@ 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.
>
>Ditto for write.

Ack

>
>> @@ -559,6 +582,8 @@ 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;
>>  }
>>
>> @@ -743,6 +768,13 @@ static int at24_probe(struct i2c_client *client,
>> const struct i2c_device_id *id)
>>
>>  	i2c_set_clientdata(client, at24);
>>
>> +	/* enable runtime pm */
>> +	err = pm_runtime_set_active(&client->dev);
>> +	if (err < 0)
>> +		goto err_clients;
>> +
>> +	pm_runtime_enable(&client->dev);
>> +
>
>Here, too: at24_read() below can fail, as well as nvmem_register().

Ack
In addition to that calling pm_runtime_get_noresume before enabling pm.

>
>>  	/*
>>  	 * Perform a one-byte test read to verify that the
>>  	 * chip is functional.
>> @@ -810,6 +842,8 @@ static int at24_remove(struct i2c_client *client)
>>  	for (i = 1; i < at24->num_addresses; i++)
>>  		i2c_unregister_device(at24->client[i]);
>>
>> +	pm_runtime_disable(&client->dev);
>
>pm_runtime_set_suspended(&client->dev)

Ack

>
>> +
>>  	return 0;
>>  }
>>
>
>--
>Regards,
>
>Sakari Ailus
>e-mail: sakari.ailus@iki.fi

Patch

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 2199c42..0d26681 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -24,6 +24,7 @@ 
 #include <linux/i2c.h>
 #include <linux/nvmem-provider.h>
 #include <linux/platform_data/at24.h>
+#include <linux/pm_runtime.h>
 
 /*
  * 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.
@@ -527,17 +538,29 @@  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.
@@ -559,6 +582,8 @@  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;
 }
 
@@ -743,6 +768,13 @@  static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 
 	i2c_set_clientdata(client, at24);
 
+	/* enable runtime pm */
+	err = pm_runtime_set_active(&client->dev);
+	if (err < 0)
+		goto err_clients;
+
+	pm_runtime_enable(&client->dev);
+
 	/*
 	 * Perform a one-byte test read to verify that the
 	 * chip is functional.
@@ -810,6 +842,8 @@  static int at24_remove(struct i2c_client *client)
 	for (i = 1; i < at24->num_addresses; i++)
 		i2c_unregister_device(at24->client[i]);
 
+	pm_runtime_disable(&client->dev);
+
 	return 0;
 }