From: Sakari Ailus <sakari.ailus@linux.intel.com>
To: linux-i2c@vger.kernel.org
Cc: Wolfram Sang <wsa@the-dreams.de>,
"Rafael J. Wysocki" <rafael@kernel.org>,
linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
rajmohan.mani@intel.com, Tomasz Figa <tfiga@chromium.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Bingbu Cao <bingbu.cao@intel.com>,
Chiranjeevi Rapolu <chiranjeevi.rapolu@intel.com>,
Hyungwoo Yang <hyungwoo.yang@intel.com>,
linux-media@vger.kernel.org
Subject: [PATCH v7 5/6] at24: Support probing while off
Date: Wed, 2 Sep 2020 00:03:32 +0300 [thread overview]
Message-ID: <20200901210333.8462-6-sakari.ailus@linux.intel.com> (raw)
In-Reply-To: <20200901210333.8462-1-sakari.ailus@linux.intel.com>
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@linux.intel.com>
---
drivers/misc/eeprom/at24.c | 43 +++++++++++++++++++++++---------------
1 file changed, 26 insertions(+), 17 deletions(-)
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 2591c21b2b5d8..a343e55e41126 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -561,6 +561,7 @@ 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;
@@ -698,25 +699,30 @@ static int at24_probe(struct i2c_client *client)
i2c_set_clientdata(client, at24);
- err = regulator_enable(at24->vcc_reg);
- if (err) {
- dev_err(dev, "Failed to enable vcc regulator\n");
- return err;
- }
+ low_power = acpi_dev_state_low_power(&client->dev);
+ if (!low_power) {
+ err = regulator_enable(at24->vcc_reg);
+ if (err) {
+ dev_err(dev, "Failed to enable vcc regulator\n");
+ return err;
+ }
- /* enable runtime pm */
- pm_runtime_set_active(dev);
+ 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);
- if (err) {
- pm_runtime_disable(dev);
- regulator_disable(at24->vcc_reg);
- return -ENODEV;
+ if (!low_power) {
+ err = at24_read(at24, 0, &test_byte, 1);
+ if (err) {
+ pm_runtime_disable(dev);
+ regulator_disable(at24->vcc_reg);
+ return -ENODEV;
+ }
}
pm_runtime_idle(dev);
@@ -736,9 +742,11 @@ static int at24_remove(struct i2c_client *client)
struct at24_data *at24 = i2c_get_clientdata(client);
pm_runtime_disable(&client->dev);
- if (!pm_runtime_status_suspended(&client->dev))
- regulator_disable(at24->vcc_reg);
- pm_runtime_set_suspended(&client->dev);
+ if (!acpi_dev_state_low_power(&client->dev)) {
+ if (!pm_runtime_status_suspended(&client->dev))
+ regulator_disable(at24->vcc_reg);
+ pm_runtime_set_suspended(&client->dev);
+ }
return 0;
}
@@ -775,6 +783,7 @@ static struct i2c_driver at24_driver = {
.probe_new = at24_probe,
.remove = at24_remove,
.id_table = at24_ids,
+ .flags = I2C_DRV_FL_ALLOW_LOW_POWER_PROBE,
};
static int __init at24_init(void)
--
2.20.1
next prev parent reply other threads:[~2020-09-01 21:03 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 21:03 [PATCH v7 0/6] Support running driver's probe for a device powered off Sakari Ailus
2020-09-01 21:03 ` [PATCH v7 1/6] i2c: Allow an ACPI driver to manage the device's power state during probe Sakari Ailus
2020-09-01 21:03 ` [PATCH v7 2/6] ACPI: Add a convenience function to tell a device is in low power state Sakari Ailus
2020-09-01 21:03 ` [PATCH v7 3/6] ov5670: Support probe whilst the device is in a " Sakari Ailus
2020-09-01 21:03 ` [PATCH v7 4/6] media: i2c: imx319: Support probe while the device is off Sakari Ailus
2020-09-01 21:03 ` Sakari Ailus [this message]
2020-09-01 21:03 ` [PATCH v7 6/6] Documentation: ACPI: Document allow-low-power-probe _DSD property Sakari Ailus
2020-09-02 15:57 ` Rafael J. Wysocki
2020-09-02 16:31 ` Sakari Ailus
2020-09-02 16:34 ` Rafael J. Wysocki
2020-09-02 19:59 ` Sakari Ailus
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