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.mohand...@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;
> }
>
--
Regards,
Sakari Ailus
e-mail: sakari.ai...@iki.fi
