Hi Sakari, Thanks for the review. My comments below.
--- ^Divagar >-----Original Message----- >From: Sakari Ailus [mailto:sakari.ai...@iki.fi] >Sent: Thursday, August 31, 2017 2:50 AM >To: Mohandass, Divagar <divagar.mohand...@intel.com> >Cc: robh...@kernel.org; mark.rutl...@arm.com; w...@the-dreams.de; >devicet...@vger.kernel.org; linux-...@vger.kernel.org; linux- >ker...@vger.kernel.org; Mani, Rajmohan <rajmohan.m...@intel.com> >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.mohand...@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. > 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.ai...@iki.fi
