Hi Sakari, Thanks for your review comments. My comments below. --- ^Divagar >-----Original Message----- >From: Sakari Ailus [mailto:sakari.ailus@xxxxxx] >Sent: Tuesday, August 22, 2017 2:26 PM >To: Mohandass, Divagar <divagar.mohandass@xxxxxxxxx> >Cc: robh+dt@xxxxxxxxxx; mark.rutland@xxxxxxx; wsa@xxxxxxxxxxxxx; >devicetree@xxxxxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; linux- >kernel@xxxxxxxxxxxxxxx; Mani, Rajmohan <rajmohan.mani@xxxxxxxxx> >Subject: Re: [PATCH v2 3/3] eeprom: at24: enable runtime pm support > >Hi Divagar, > >Thanks for the patch. Please see my comments below. > >On Tue, Aug 15, 2017 at 12:11:59AM +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@xxxxxxxxx> >> --- >> drivers/misc/eeprom/at24.c | 34 ++++++++++++++++++++++++++++++++++ >> 1 file changed, 34 insertions(+) >> >> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c >> index 2199c42..0d26681 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; >> + } >> + > >at24_read() may fail between the two chunks here. You'll need >pm_runtime_put() before returning the error code. Ack > >> /* >> * Read data from chip, protecting against concurrent updates >> * from this host, but not from other I2C masters. >> @@ -527,17 +538,29 @@ 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. > >Ditto for write. Ack > >> @@ -559,6 +582,8 @@ 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 +768,13 @@ static int at24_probe(struct i2c_client *client, >> const struct i2c_device_id *id) >> >> i2c_set_clientdata(client, at24); >> >> + /* enable runtime pm */ >> + err = pm_runtime_set_active(&client->dev); >> + if (err < 0) >> + goto err_clients; >> + >> + pm_runtime_enable(&client->dev); >> + > >Here, too: at24_read() below can fail, as well as nvmem_register(). Ack In addition to that calling pm_runtime_get_noresume before enabling pm. > >> /* >> * Perform a one-byte test read to verify that the >> * chip is functional. >> @@ -810,6 +842,8 @@ 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) Ack > >> + >> return 0; >> } >> > >-- >Regards, > >Sakari Ailus >e-mail: sakari.ailus@xxxxxx
