[PATCH v4 0/3] enable eeprom "size" property and runtime pm

[PATCH v4 0/3] enable eeprom "size" property and runtime pm

[Divagar Mohandass]

This series adds support for eeprom "size" property which will be read by the
driver for eeprom size. The existing ACPI has a different default size which
can be overridden with a DSD property value provided by the platform FW.

This series also adds support for runtime PM. The eeprom driver currently
did not have support for runtime PM and the device was kept in D0 throughout.

[v1]
- Add support for eeprom "size" property.
- Add runtime PM support to the driver.

[v2]
- Improved the patch subject.

[v3]
- Addressed comments from Sakari Ailus.
- Improved patch description.
- Improved pm support patch.

[v4]
- Improved runtime pm support.
- Addressed comments from Sakari Ailus.

Divagar Mohandass (3):
  dt-bindings: add eeprom "size" property
  eeprom: at24: add support to fetch eeprom device property "size"
  eeprom: at24: enable runtime pm support

 .../devicetree/bindings/eeprom/eeprom.txt          |  2 +
 drivers/misc/eeprom/at24.c                         | 44 ++++++++++++++++++++++
 2 files changed, 46 insertions(+)

-- 
1.9.1

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[PATCH v4 1/3] dt-bindings: add eeprom "size" property

[Divagar Mohandass]

This adds eeprom "size" as optional property for i2c eeproms.
The "size" property allows explicitly specifying the size of the
EEPROM chip in bytes.

Signed-off-by: Divagar Mohandass <divagar.mohandass-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 Documentation/devicetree/bindings/eeprom/eeprom.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/eeprom/eeprom.txt b/Documentation/devicetree/bindings/eeprom/eeprom.txt
index 5696eb5..1436569 100644
--- a/Documentation/devicetree/bindings/eeprom/eeprom.txt
+++ b/Documentation/devicetree/bindings/eeprom/eeprom.txt
@@ -32,6 +32,8 @@ Optional properties:
 
   - read-only: this parameterless property disables writes to the eeprom
 
+  - size: total eeprom size in bytes
+
 Example:
 
 eeprom@52 {
-- 
1.9.1

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Re: [PATCH v4 1/3] dt-bindings: add eeprom "size" property

[Rob Herring]

On Wed, Aug 30, 2017 at 10:35:38PM +0530, Divagar Mohandass wrote:
> This adds eeprom "size" as optional property for i2c eeproms.
> The "size" property allows explicitly specifying the size of the
> EEPROM chip in bytes.
> 
> Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
> ---
>  Documentation/devicetree/bindings/eeprom/eeprom.txt | 2 ++
>  1 file changed, 2 insertions(+)

Please add acks when posting new versions or state here why you didn't.

Acked-by: Rob Herring <robh@kernel.org>

RE: [PATCH v4 1/3] dt-bindings: add eeprom "size" property

[Mohandass, Divagar]

Hi Rob,

Sorry I missed it, will follow from next version.

---
^Divagar

>-----Original Message-----
>From: Rob Herring [mailto:robh@kernel.org]
>Sent: Thursday, August 31, 2017 8:56 PM
>To: Mohandass, Divagar <divagar.mohandass@intel.com>
>Cc: mark.rutland@arm.com; wsa@the-dreams.de; sakari.ailus@iki.fi;
>devicetree@vger.kernel.org; linux-i2c@vger.kernel.org; linux-
>kernel@vger.kernel.org; Mani, Rajmohan <rajmohan.mani@intel.com>
>Subject: Re: [PATCH v4 1/3] dt-bindings: add eeprom "size" property
>
>On Wed, Aug 30, 2017 at 10:35:38PM +0530, Divagar Mohandass wrote:
>> This adds eeprom "size" as optional property for i2c eeproms.
>> The "size" property allows explicitly specifying the size of the
>> EEPROM chip in bytes.
>>
>> Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
>> ---
>>  Documentation/devicetree/bindings/eeprom/eeprom.txt | 2 ++
>>  1 file changed, 2 insertions(+)
>
>Please add acks when posting new versions or state here why you didn't.
>
>Acked-by: Rob Herring <robh@kernel.org>

[PATCH v4 2/3] eeprom: at24: add support to fetch eeprom device property "size"

[Divagar Mohandass]

Obtain the size of the EEPROM chip from DT if the "size" property is
specified for the device.

Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
---
 drivers/misc/eeprom/at24.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 764ff5df..2199c42 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -570,6 +570,10 @@ static void at24_get_pdata(struct device *dev, struct at24_platform_data *chip)
 	if (device_property_present(dev, "read-only"))
 		chip->flags |= AT24_FLAG_READONLY;
 
+	err = device_property_read_u32(dev, "size", &val);
+	if (!err)
+		chip->byte_len = val;
+
 	err = device_property_read_u32(dev, "pagesize", &val);
 	if (!err) {
 		chip->page_size = val;
-- 
1.9.1

[PATCH v4 3/3] eeprom: at24: enable runtime pm support

[Divagar Mohandass]

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 | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 2199c42..65a7d83 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.
@@ -518,6 +529,7 @@ static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 		status = at24->read_func(at24, buf, off, count);
 		if (status < 0) {
 			mutex_unlock(&at24->lock);
+			pm_runtime_put(&client->dev);
 			return status;
 		}
 		buf += status;
@@ -527,17 +539,29 @@ 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.
@@ -550,6 +574,7 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 		status = at24->write_func(at24, buf, off, count);
 		if (status < 0) {
 			mutex_unlock(&at24->lock);
+			pm_runtime_put(&client->dev);
 			return status;
 		}
 		buf += status;
@@ -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 +770,14 @@ 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);
+
 	/*
 	 * Perform a one-byte test read to verify that the
 	 * chip is functional.
@@ -753,6 +788,8 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		goto err_clients;
 	}
 
+	pm_runtime_put(&client->dev);
+
 	at24->nvmem_config.name = dev_name(&client->dev);
 	at24->nvmem_config.dev = &client->dev;
 	at24->nvmem_config.read_only = !writable;
@@ -810,6 +847,9 @@ 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;
 }
 
-- 
1.9.1

Re: [PATCH v4 3/3] eeprom: at24: enable runtime pm support

[Sakari Ailus]

Hi Divagar,

Thanks for the update.

On Wed, Aug 30, 2017 at 10:35:40PM +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 | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index 2199c42..65a7d83 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.
> @@ -518,6 +529,7 @@ static int at24_read(void *priv, unsigned int off, void *val, size_t count)
>  		status = at24->read_func(at24, buf, off, count);
>  		if (status < 0) {
>  			mutex_unlock(&at24->lock);
> +			pm_runtime_put(&client->dev);
>  			return status;
>  		}
>  		buf += status;
> @@ -527,17 +539,29 @@ 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.
> @@ -550,6 +574,7 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
>  		status = at24->write_func(at24, buf, off, count);
>  		if (status < 0) {
>  			mutex_unlock(&at24->lock);
> +			pm_runtime_put(&client->dev);
>  			return status;
>  		}
>  		buf += status;
> @@ -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 +770,14 @@ 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;

Btw. I don't think pm_runtime_set_active() can fail here. In other words
it'd be fine to ignore the return value.

> +
> +	pm_runtime_enable(&client->dev);
> +
>  	/*
>  	 * Perform a one-byte test read to verify that the
>  	 * chip is functional.
> @@ -753,6 +788,8 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  		goto err_clients;

I suppose the runtime PM state is re-initialised for a device when a driver
is probed, but it'd still be nice to decrement the use count if this fails.
You should also disable PM runtime if probe fails and set the device
suspended again.

Same for other error cases. I think you'll need a new label.

>  	}
>  
> +	pm_runtime_put(&client->dev);
> +
>  	at24->nvmem_config.name = dev_name(&client->dev);
>  	at24->nvmem_config.dev = &client->dev;
>  	at24->nvmem_config.read_only = !writable;
> @@ -810,6 +847,9 @@ 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

RE: [PATCH v4 3/3] eeprom: at24: enable runtime pm support

[Mohandass, Divagar]

Hi Sakari,

Thanks for the review.
My comments below.

---
^Divagar

>-----Original Message-----
>From: Sakari Ailus [mailto:sakari.ailus-X3B1VOXEql0@public.gmane.org]
>Sent: Thursday, August 31, 2017 2:50 AM
>To: Mohandass, Divagar <divagar.mohandass-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>Cc: robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org; mark.rutland-5wv7dgnIgG8@public.gmane.org; wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org;
>devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-
>kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Mani, Rajmohan <rajmohan.mani-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>Subject: Re: [PATCH v4 3/3] eeprom: at24: enable runtime pm support
>
>Hi Divagar,
>
>Thanks for the update.
>
>On Wed, Aug 30, 2017 at 10:35:40PM +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-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>> ---
>>  drivers/misc/eeprom/at24.c | 40
>> ++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 40 insertions(+)
>>
>> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
>> index 2199c42..65a7d83 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.
>> @@ -518,6 +529,7 @@ static int at24_read(void *priv, unsigned int off,
>void *val, size_t count)
>>  		status = at24->read_func(at24, buf, off, count);
>>  		if (status < 0) {
>>  			mutex_unlock(&at24->lock);
>> +			pm_runtime_put(&client->dev);
>>  			return status;
>>  		}
>>  		buf += status;
>> @@ -527,17 +539,29 @@ 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.
>> @@ -550,6 +574,7 @@ static int at24_write(void *priv, unsigned int off,
>void *val, size_t count)
>>  		status = at24->write_func(at24, buf, off, count);
>>  		if (status < 0) {
>>  			mutex_unlock(&at24->lock);
>> +			pm_runtime_put(&client->dev);
>>  			return status;
>>  		}
>>  		buf += status;
>> @@ -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 +770,14 @@ 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;
>
>Btw. I don't think pm_runtime_set_active() can fail here. In other words it'd be
>fine to ignore the return value.
>

Ack


>> +
>> +	pm_runtime_enable(&client->dev);
>> +
>>  	/*
>>  	 * Perform a one-byte test read to verify that the
>>  	 * chip is functional.
>> @@ -753,6 +788,8 @@ static int at24_probe(struct i2c_client *client, const
>struct i2c_device_id *id)
>>  		goto err_clients;
>
>I suppose the runtime PM state is re-initialised for a device when a driver is
>probed, but it'd still be nice to decrement the use count if this fails.

Ack

>You should also disable PM runtime if probe fails and set the device
>suspended again.
>
>Same for other error cases. I think you'll need a new label.
>

Can I disable PM runtime and set suspend in the 'err_clients' label itself ?

>>  	}
>>
>> +	pm_runtime_put(&client->dev);
>> +
>>  	at24->nvmem_config.name = dev_name(&client->dev);
>>  	at24->nvmem_config.dev = &client->dev;
>>  	at24->nvmem_config.read_only = !writable; @@ -810,6 +847,9 @@
>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-X3B1VOXEql0@public.gmane.org
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Re: [PATCH v4 3/3] eeprom: at24: enable runtime pm support

[Sakari Ailus]

On Thu, Aug 31, 2017 at 11:24:38AM +0000, Mohandass, Divagar wrote:
> >> @@ -743,6 +770,14 @@ 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;
> >
> >Btw. I don't think pm_runtime_set_active() can fail here. In other words it'd be
> >fine to ignore the return value.
> >
> 
> Ack
> 
> 
> >> +
> >> +	pm_runtime_enable(&client->dev);
> >> +
> >>  	/*
> >>  	 * Perform a one-byte test read to verify that the
> >>  	 * chip is functional.
> >> @@ -753,6 +788,8 @@ static int at24_probe(struct i2c_client *client, const
> >struct i2c_device_id *id)
> >>  		goto err_clients;
> >
> >I suppose the runtime PM state is re-initialised for a device when a driver is
> >probed, but it'd still be nice to decrement the use count if this fails.
> 
> Ack
> 
> >You should also disable PM runtime if probe fails and set the device
> >suspended again.
> >
> >Same for other error cases. I think you'll need a new label.
> >
> 
> Can I disable PM runtime and set suspend in the 'err_clients' label itself ?

Disable, yes, but the get and put calls need to be balanced.

-- 
Sakari Ailus
e-mail: sakari.ailus@iki.fi

RE: [PATCH v4 3/3] eeprom: at24: enable runtime pm support

[Mohandass, Divagar]

Hi Sakari,

Thanks for the review.
My comments below.

---
^Divagar

>-----Original Message-----
>From: Sakari Ailus [mailto:sakari.ailus-X3B1VOXEql0@public.gmane.org]
>Sent: Thursday, August 31, 2017 9:07 PM
>To: Mohandass, Divagar <divagar.mohandass-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>Cc: robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org; mark.rutland-5wv7dgnIgG8@public.gmane.org; wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org;
>devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-
>kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Mani, Rajmohan <rajmohan.mani-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>Subject: Re: [PATCH v4 3/3] eeprom: at24: enable runtime pm support
>
>On Thu, Aug 31, 2017 at 11:24:38AM +0000, Mohandass, Divagar wrote:
>> >> @@ -743,6 +770,14 @@ 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;
>> >
>> >Btw. I don't think pm_runtime_set_active() can fail here. In other
>> >words it'd be fine to ignore the return value.
>> >
>>
>> Ack
>>
>>
>> >> +
>> >> +	pm_runtime_enable(&client->dev);
>> >> +
>> >>  	/*
>> >>  	 * Perform a one-byte test read to verify that the
>> >>  	 * chip is functional.
>> >> @@ -753,6 +788,8 @@ static int at24_probe(struct i2c_client
>> >> *client, const
>> >struct i2c_device_id *id)
>> >>  		goto err_clients;
>> >
>> >I suppose the runtime PM state is re-initialised for a device when a
>> >driver is probed, but it'd still be nice to decrement the use count if this
>fails.
>>
>> Ack
>>
>> >You should also disable PM runtime if probe fails and set the device
>> >suspended again.
>> >
>> >Same for other error cases. I think you'll need a new label.
>> >
>>
>> Can I disable PM runtime and set suspend in the 'err_clients' label itself ?
>
>Disable, yes, but the get and put calls need to be balanced.

We are performing pm_runtime_put after the first read check and in the error condition, so PM runtime disable alone should be sufficient in the 'err_clients' label.
I think it is balanced, your comments ?

>
>--
>Sakari Ailus
>e-mail: sakari.ailus-X3B1VOXEql0@public.gmane.org
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