Hi Sakari, Thanks for your time. My comments below.
--- ^Divagar >-----Original Message----- >From: Sakari Ailus [mailto:sakari.ai...@iki.fi] >Sent: Wednesday, August 30, 2017 1:24 PM >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 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.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? 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.ai...@iki.fi
