[v3,3/3] eeprom: at24: enable runtime pm support

Message ID 1504066266-30051-4-git-send-email-divagar.mohandass@intel.com
State New
Headers show
Series
  • enable eeprom "size" property and runtime pm
Related show

Commit Message

Mohandass, Divagar Aug. 30, 2017, 4:11 a.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 | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

Comments

Sakari Ailus Aug. 30, 2017, 7:53 a.m. | #1
Hi Divagar,

Thanks for the update. A few more comments below.

On Wed, Aug 30, 2017 at 09:41:06AM +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 | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index 2199c42..a670814 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 +502,22 @@ 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);
> +		pm_runtime_put(&client->dev);

Two puts are too much here. How about dropping this one?

> +		return ret;
> +	}
> +
>  	/*
>  	 * Read data from chip, protecting against concurrent updates
>  	 * from this host, but not from other I2C masters.

If an error happens between the two chunks, you'll need pm_runtime_put(),
too.

> @@ -527,17 +539,30 @@ 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);
> +		pm_runtime_put(&client->dev);

Same here.

> +		return ret;
> +	}
> +
>  	/*
>  	 * Write data to chip, protecting against concurrent updates
>  	 * from this host, but not from other I2C masters.

Ditto.

> @@ -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;
>  }
>  
> @@ -743,6 +770,15 @@ 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);
> +	err = pm_runtime_set_active(&client->dev);
> +	if (err < 0)
> +		goto err_clients;
> +
> +	pm_runtime_enable(&client->dev);
> +	pm_runtime_put(&client->dev);
> +

You're just about to perform a read here. I believe you should move the
last put after that.

>  	/*
>  	 * Perform a one-byte test read to verify that the
>  	 * chip is functional.
> @@ -810,6 +846,9 @@ 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;
>  }
>
Mohandass, Divagar Aug. 30, 2017, 12:32 p.m. | #2
Hi Sakari,

Thanks for your time.
My comments below.

---
^Divagar

>-----Original Message-----
>From: Sakari Ailus [mailto:sakari.ailus@iki.fi]
>Sent: Wednesday, August 30, 2017 1:24 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 v3 3/3] eeprom: at24: enable runtime pm support
>
>Hi Divagar,
>
>Thanks for the update. A few more comments below.
>
>On Wed, Aug 30, 2017 at 09:41:06AM +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 | 39
>> +++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 39 insertions(+)
>>
>> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
>> index 2199c42..a670814 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 +502,22 @@ 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);
>> +		pm_runtime_put(&client->dev);
>
>Two puts are too much here. How about dropping this one?

Ack
Will fix in next version.

>
>> +		return ret;
>> +	}
>> +
>>  	/*
>>  	 * Read data from chip, protecting against concurrent updates
>>  	 * from this host, but not from other I2C masters.
>
>If an error happens between the two chunks, you'll need pm_runtime_put(),
>too.
>

Ack

>> @@ -527,17 +539,30 @@ 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);
>> +		pm_runtime_put(&client->dev);
>
>Same here.
>

Ack

>> +		return ret;
>> +	}
>> +
>>  	/*
>>  	 * Write data to chip, protecting against concurrent updates
>>  	 * from this host, but not from other I2C masters.
>
>Ditto.

Ack

>
>> @@ -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;
>>  }
>>
>> @@ -743,6 +770,15 @@ 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);
>> +	err = pm_runtime_set_active(&client->dev);
>> +	if (err < 0)
>> +		goto err_clients;
>> +
>> +	pm_runtime_enable(&client->dev);
>> +	pm_runtime_put(&client->dev);
>> +
>
>You're just about to perform a read here. I believe you should move the last
>put after that.

At the end of at24_read we are performing a pm_runtime_put, still we need this change ?

>
>>  	/*
>>  	 * Perform a one-byte test read to verify that the
>>  	 * chip is functional.
>> @@ -810,6 +846,9 @@ 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;
>>  }
>>
>
>--
>Regards,
>
>Sakari Ailus
>e-mail: sakari.ailus@iki.fi
Sakari Ailus Aug. 30, 2017, 12:41 p.m. | #3
On Wed, Aug 30, 2017 at 12:32:07PM +0000, Mohandass, Divagar wrote:
> >> @@ -743,6 +770,15 @@ 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);
> >> +	err = pm_runtime_set_active(&client->dev);
> >> +	if (err < 0)
> >> +		goto err_clients;
> >> +
> >> +	pm_runtime_enable(&client->dev);
> >> +	pm_runtime_put(&client->dev);
> >> +
> >
> >You're just about to perform a read here. I believe you should move the last
> >put after that.
> 
> At the end of at24_read we are performing a pm_runtime_put, still we need this change ?

True, so this isn't an actual problem.

It'll still power the chip down when you're about to need it, so it'd make
sense to perform the check before pm_runtime_put().

I might move the runtime PM setup after the check altogether.
Mohandass, Divagar Aug. 30, 2017, 5:04 p.m. | #4
Hi Sakari,

Thanks for the review.
My comments below.

---
^Divagar

>-----Original Message-----
>From: Sakari Ailus [mailto:sakari.ailus@iki.fi]
>Sent: Wednesday, August 30, 2017 6:11 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 v3 3/3] eeprom: at24: enable runtime pm support
>
>On Wed, Aug 30, 2017 at 12:32:07PM +0000, Mohandass, Divagar wrote:
>> >> @@ -743,6 +770,15 @@ 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);
>> >> +	err = pm_runtime_set_active(&client->dev);
>> >> +	if (err < 0)
>> >> +		goto err_clients;
>> >> +
>> >> +	pm_runtime_enable(&client->dev);
>> >> +	pm_runtime_put(&client->dev);
>> >> +
>> >
>> >You're just about to perform a read here. I believe you should move
>> >the last put after that.
>>
>> At the end of at24_read we are performing a pm_runtime_put, still we need
>this change ?
>
>True, so this isn't an actual problem.
>
>It'll still power the chip down when you're about to need it, so it'd make sense
>to perform the check before pm_runtime_put().
>
>I might move the runtime PM setup after the check altogether.

Ok, I will move the pm_runtime_put() after the check and publish the v4.
Moving the PM setup altogether below, will introduce more error handling in read call.

>
>--
>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..a670814 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 +502,22 @@  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);
+		pm_runtime_put(&client->dev);
+		return ret;
+	}
+
 	/*
 	 * Read data from chip, protecting against concurrent updates
 	 * from this host, but not from other I2C masters.
@@ -527,17 +539,30 @@  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);
+		pm_runtime_put(&client->dev);
+		return ret;
+	}
+
 	/*
 	 * Write data to chip, protecting against concurrent updates
 	 * from this host, but not from other I2C masters.
@@ -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;
 }
 
@@ -743,6 +770,15 @@  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);
+	err = pm_runtime_set_active(&client->dev);
+	if (err < 0)
+		goto err_clients;
+
+	pm_runtime_enable(&client->dev);
+	pm_runtime_put(&client->dev);
+
 	/*
 	 * Perform a one-byte test read to verify that the
 	 * chip is functional.
@@ -810,6 +846,9 @@  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;
 }