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Date: Tue, 21 Jan 2020 15:41:56 +0200 From: Sakari Ailus <sakari.ailus@...ux.intel.com> To: linux-i2c@...r.kernel.org Cc: Wolfram Sang <wsa@...-dreams.de>, "Rafael J. Wysocki" <rafael@...nel.org>, linux-acpi@...r.kernel.org, Bingbu Cao <bingbu.cao@...el.com>, linux-media@...r.kernel.org, Chiranjeevi Rapolu <chiranjeevi.rapolu@...el.com>, Hyungwoo Yang <hyungwoo.yang@...el.com>, Bartosz Golaszewski <bgolaszewski@...libre.com>, Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, rajmohan.mani@...el.com, Tomasz Figa <tfiga@...omium.org> Subject: [PATCH v4 5/6] at24: Support probing while off In certain use cases (where the chip is part of a camera module, and the camera module is wired together with a camera privacy LED), powering on the device during probe is undesirable. Add support for the at24 to execute probe while being powered off. For this to happen, a hint in form of a device property is required from the firmware. Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com> --- drivers/misc/eeprom/at24.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index 0681d5fdd538a..5fc1162b67618 100644 --- a/drivers/misc/eeprom/at24.c +++ b/drivers/misc/eeprom/at24.c @@ -564,6 +564,7 @@ static int at24_probe(struct i2c_client *client) bool i2c_fn_i2c, i2c_fn_block; unsigned int i, num_addresses; struct at24_data *at24; + bool low_power; struct regmap *regmap; bool writable; u8 test_byte; @@ -701,19 +702,24 @@ static int at24_probe(struct i2c_client *client) i2c_set_clientdata(client, at24); - /* enable runtime pm */ - pm_runtime_set_active(dev); + low_power = acpi_dev_state_low_power(&client->dev); + if (!low_power) + pm_runtime_set_active(dev); + pm_runtime_enable(dev); /* - * Perform a one-byte test read to verify that the - * chip is functional. + * Perform a one-byte test read to verify that the chip is functional, + * unless powering on the device is to be avoided during probe (i.e. + * it's powered off right now). */ - err = at24_read(at24, 0, &test_byte, 1); - pm_runtime_idle(dev); - if (err) { - pm_runtime_disable(dev); - return -ENODEV; + if (!low_power) { + err = at24_read(at24, 0, &test_byte, 1); + pm_runtime_idle(dev); + if (err) { + pm_runtime_disable(dev); + return -ENODEV; + } } if (writable) @@ -728,8 +734,12 @@ static int at24_probe(struct i2c_client *client) static int at24_remove(struct i2c_client *client) { + bool low_power; + pm_runtime_disable(&client->dev); - pm_runtime_set_suspended(&client->dev); + low_power = acpi_dev_state_low_power(&client->dev); + if (!low_power) + pm_runtime_set_suspended(&client->dev); return 0; } @@ -743,6 +753,7 @@ static struct i2c_driver at24_driver = { .probe_new = at24_probe, .remove = at24_remove, .id_table = at24_ids, + .probe_low_power = true, }; static int __init at24_init(void) -- 2.20.1
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