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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>
Subject: [PATCH v3 5/5] at24: Support probing while off
Date: Thu,  9 Jan 2020 17:45:29 +0200
Message-ID: <20200109154529.19484-6-sakari.ailus@linux.intel.com> (raw)
In-Reply-To: <20200109154529.19484-1-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 | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 0681d5fdd538a..41ac65d1e5d41 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_low_power_state_probe(&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_low_power_state_probe(&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


  parent reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-09 15:45 [PATCH v3 0/5] Support running driver's probe for a device powered off Sakari Ailus
2020-01-09 15:45 ` [PATCH v3 1/5] i2c: Allow driver to manage the device's power state during probe Sakari Ailus
2020-01-09 15:45 ` [PATCH v3 2/5] ACPI: Add a convenience function to tell a device is suspended in probe Sakari Ailus
2020-01-13 10:41   ` Rafael J. Wysocki
2020-01-21  9:09     ` Sakari Ailus
2020-01-21 16:02       ` Rafael J. Wysocki
2020-01-09 15:45 ` [PATCH v3 3/5] ov5670: Support probe whilst the device is in a low power state Sakari Ailus
2020-01-09 15:45 ` [PATCH v3 4/5] media: i2c: imx319: Support probe while the device is off Sakari Ailus
2020-01-09 15:45 ` Sakari Ailus [this message]
2020-01-10 11:16   ` [PATCH v3 5/5] at24: Support probing while off Bartosz Golaszewski
2020-01-10 11:28     ` Sakari Ailus
2020-01-10 11:31       ` Bartosz Golaszewski

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