On Fri, 2019-10-18 at 18:24 +0900, Tomasz Figa wrote:
> Hi Bibby,
>
> On Fri, Oct 18, 2019 at 5:26 PM Bibby Hsieh <bibby.hsieh@xxxxxxxxxxxx> wrote:
> >
> > Although in the most platforms, the power of eeprom and i2c
> > are alway on, some platforms disable the eeprom and i2c power
> > in order to meet low power request.
> > This patch add the pm_runtime ops to control power to support
> > all platforms.
> >
> > Changes since v3:
> > - remove redundant calling function
> > - change SIMPLE_DEV_PM_OPS to SET_RUNTIME_PM_OPS
> > - change supply name
> >
> > Changes since v2:
> > - rebase onto v5.4-rc1
> > - pm_runtime_disable and regulator_bulk_disable at
> > err return in probe function
> >
> > Changes since v1:
> > - remove redundant code
> > - fixup coding style
> >
> > Signed-off-by: Bibby Hsieh <bibby.hsieh@xxxxxxxxxxxx>
> > ---
> > drivers/misc/eeprom/at24.c | 64 ++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 64 insertions(+)
> >
> > diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> > index 2cccd82a3106..68ced4f25916 100644
> > --- a/drivers/misc/eeprom/at24.c
> > +++ b/drivers/misc/eeprom/at24.c
> > @@ -22,6 +22,7 @@
> > #include <linux/nvmem-provider.h>
> > #include <linux/regmap.h>
> > #include <linux/pm_runtime.h>
> > +#include <linux/regulator/consumer.h>
> > #include <linux/gpio/consumer.h>
> >
> > /* Address pointer is 16 bit. */
> > @@ -67,6 +68,12 @@
> > * which won't work on pure SMBus systems.
> > */
> >
> > +static const char * const at24_supply_names[] = {
> > + "vcc", "i2c",
> > +};
> > +
> > +#define AT24_NUM_SUPPLIES ARRAY_SIZE(at24_supply_names)
> > +
> > struct at24_client {
> > struct i2c_client *client;
> > struct regmap *regmap;
> > @@ -91,6 +98,8 @@ struct at24_data {
> >
> > struct gpio_desc *wp_gpio;
> >
> > + bool has_supplies;
> > + struct regulator_bulk_data supplies[AT24_NUM_SUPPLIES];
> > /*
> > * Some chips tie up multiple I2C addresses; dummy devices reserve
> > * them for us, and we'll use them with SMBus calls.
> > @@ -662,6 +671,17 @@ static int at24_probe(struct i2c_client *client)
> > at24->client[0].client = client;
> > at24->client[0].regmap = regmap;
> >
> > + regulator_bulk_set_supply_names(at24->supplies,
> > + at24_supply_names, AT24_NUM_SUPPLIES);
> > + err = devm_regulator_bulk_get(&at24->client[0].client->dev,
> > + AT24_NUM_SUPPLIES, at24->supplies);
> > + if (err == -ENODEV)
> > + at24->has_supplies = NULL;
>
> has_supplies is a bool, so the right value would be false.
>
> > + else if (err == 0)
>
> nit: One would typically use !err here as the condition.
>
> > + at24->has_supplies = !err;
>
> In this branch, err is always 0, so !err is always true and we can
> just directly assign true to the field.
Got it.
>
> > + else
> > + return err;
> > +
> > at24->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_HIGH);
> > if (IS_ERR(at24->wp_gpio))
> > return PTR_ERR(at24->wp_gpio);
> > @@ -701,6 +721,14 @@ static int at24_probe(struct i2c_client *client)
> >
> > i2c_set_clientdata(client, at24);
> >
> > + if (at24->has_supplies) {
> > + err = regulator_bulk_enable(AT24_NUM_SUPPLIES, at24->supplies);
> > + if (err) {
> > + dev_err(dev, "Failed to enable power regulators\n");
> > + return err;
> > + }
> > + }
> > +
> > /* enable runtime pm */
> > pm_runtime_set_active(dev);
> > pm_runtime_enable(dev);
> > @@ -713,6 +741,9 @@ static int at24_probe(struct i2c_client *client)
> > pm_runtime_idle(dev);
> > if (err) {
> > pm_runtime_disable(dev);
> > + if (at24->has_supplies)
> > + regulator_bulk_disable(AT24_NUM_SUPPLIES,
> > + at24->supplies);
> > return -ENODEV;
> > }
> >
> > @@ -725,15 +756,48 @@ static int at24_probe(struct i2c_client *client)
> >
> > static int at24_remove(struct i2c_client *client)
> > {
> > + struct at24_data *at24 = i2c_get_clientdata(client);
> > +
> > pm_runtime_disable(&client->dev);
> > pm_runtime_set_suspended(&client->dev);
> > + if (at24->has_supplies)
> > + regulator_bulk_disable(AT24_NUM_SUPPLIES, at24->supplies);
>
> It's a weird behavior, but pm_runtime_disable() doesn't guarantee that
> the device is actually resumed after the call returns. See [1].
> We should move the regulator disable before we call
> pm_runtime_set_suspended() and add !pm_runtime_status_suspended() as
> an additional condition to the if.
>
OK, I will modify it in the next version.
> By the way, that behavior is actually contradicting other parts of the
> runtime PM core. For example pm_runtime_active() returns true if
> dev->power.disable_depth is non-zero, but as per the above, the device
> could as well be suspended. Rafael, is this expected?
>
> [1] https://elixir.bootlin.com/linux/v5.4-rc2/source/drivers/base/power/runtime.c#L1316
>
> > +
> > + return 0;
> > +}
> > +
> > +static int __maybe_unused at24_suspend(struct device *dev)
> > +{
> > + struct i2c_client *client = to_i2c_client(dev);
> > + struct at24_data *at24 = i2c_get_clientdata(client);
> > +
> > + if (at24->has_supplies)
> > + return regulator_bulk_disable(AT24_NUM_SUPPLIES,
> > + at24->supplies);
> > +
> > + return 0;
> > +}
> > +
> > +static int __maybe_unused at24_resume(struct device *dev)
> > +{
> > + struct i2c_client *client = to_i2c_client(dev);
> > + struct at24_data *at24 = i2c_get_clientdata(client);
> > +
> > + if (at24->has_supplies)
> > + return regulator_bulk_enable(AT24_NUM_SUPPLIES,
> > + at24->supplies);
> >
> > return 0;
> > }
> >
> > +static const struct dev_pm_ops at24_pm_ops = {
> > + SET_RUNTIME_PM_OPS(at24_suspend, at24_resume, NULL)
>
> Do we also need pm_runtime_force_suspend() and
> pm_runtime_force_resume() as system sleep PM ops or it isn't possible
> for the device to be runtime active when entering the system suspend?
Yes, you're right, I will add those two function as system sleep PM ops.
>
> Best regards,
> Tomasz
