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.
> + 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.
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?
Best regards,
Tomasz
