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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, Bingbu Cao <bingbu.cao@intel.com>,
	linux-media@vger.kernel.org,
	Chiranjeevi Rapolu <chiranjeevi.rapolu@intel.com>,
	Hyungwoo Yang <hyungwoo.yang@intel.com>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	rajmohan.mani@intel.com, Tomasz Figa <tfiga@chromium.org>,
	"Qiu, Tian Shu" <tian.shu.qiu@intel.com>
Subject: [PATCH v6 1/6] i2c: Allow an ACPI driver to manage the device's power state during probe
Date: Wed, 26 Aug 2020 14:54:27 +0300
Message-ID: <20200826115432.6103-2-sakari.ailus@linux.intel.com> (raw)
In-Reply-To: <20200826115432.6103-1-sakari.ailus@linux.intel.com>

Enable drivers to tell ACPI that there's no need to power on a device for
probe. Drivers should still perform this by themselves if there's a need
to. In some cases powering on the device during probe is undesirable, and
this change enables a driver to choose what fits best for it.

Add a field called "flags" into struct i2c_driver for driver flags, and a
flag I2C_DRV_FL_ALLOW_LOW_POWER_PROBE to tell a driver supports probe in
low power state.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/i2c/i2c-core-base.c | 18 +++++++++++++++---
 include/linux/i2c.h         | 14 ++++++++++++++
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 34a9609f256da..f2683790eb0d2 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -436,6 +436,15 @@ static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
 	return irq > 0 ? irq : -ENXIO;
 }
 
+static bool allow_low_power_probe(struct device *dev)
+{
+	struct i2c_driver *driver = to_i2c_driver(dev->driver);
+
+	return driver->flags & I2C_DRV_FL_ALLOW_LOW_POWER_PROBE &&
+		is_acpi_node(dev_fwnode(dev)) &&
+		device_property_present(dev, "allow-low-power-probe");
+}
+
 static int i2c_device_probe(struct device *dev)
 {
 	struct i2c_client	*client = i2c_verify_client(dev);
@@ -514,7 +523,8 @@ static int i2c_device_probe(struct device *dev)
 	if (status < 0)
 		goto err_clear_wakeup_irq;
 
-	status = dev_pm_domain_attach(&client->dev, true);
+	status = dev_pm_domain_attach(&client->dev,
+				      !allow_low_power_probe(&client->dev));
 	if (status)
 		goto err_clear_wakeup_irq;
 
@@ -536,7 +546,8 @@ static int i2c_device_probe(struct device *dev)
 	return 0;
 
 err_detach_pm_domain:
-	dev_pm_domain_detach(&client->dev, true);
+	dev_pm_domain_detach(&client->dev,
+			     !allow_low_power_probe(&client->dev));
 err_clear_wakeup_irq:
 	dev_pm_clear_wake_irq(&client->dev);
 	device_init_wakeup(&client->dev, false);
@@ -562,7 +573,8 @@ static int i2c_device_remove(struct device *dev)
 		status = driver->remove(client);
 	}
 
-	dev_pm_domain_detach(&client->dev, true);
+	dev_pm_domain_detach(&client->dev,
+			     !allow_low_power_probe(&client->dev));
 
 	dev_pm_clear_wake_irq(&client->dev);
 	device_init_wakeup(&client->dev, false);
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index fc55ea41d3237..fec102b2a37a3 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -11,6 +11,7 @@
 #define _LINUX_I2C_H
 
 #include <linux/acpi.h>		/* for acpi_handle */
+#include <linux/bits.h>
 #include <linux/mod_devicetable.h>
 #include <linux/device.h>	/* for struct device */
 #include <linux/sched.h>	/* for completion */
@@ -217,6 +218,16 @@ enum i2c_alert_protocol {
 	I2C_PROTOCOL_SMBUS_HOST_NOTIFY,
 };
 
+/**
+ * enum i2c_driver_flags - Flags for an I2C device driver
+ *
+ * @I2C_DRV_FL_ALLOW_LOW_POWER_PROBE: Let the ACPI driver manage the device's
+ *				      power state during probe and remove
+ */
+enum i2c_driver_flags {
+	I2C_DRV_FL_ALLOW_LOW_POWER_PROBE = BIT(0),
+};
+
 /**
  * struct i2c_driver - represent an I2C device driver
  * @class: What kind of i2c device we instantiate (for detect)
@@ -231,6 +242,7 @@ enum i2c_alert_protocol {
  * @detect: Callback for device detection
  * @address_list: The I2C addresses to probe (for detect)
  * @clients: List of detected clients we created (for i2c-core use only)
+ * @flags: A bitmask of flags defined in &enum i2c_driver_flags
  *
  * The driver.owner field should be set to the module owner of this driver.
  * The driver.name field should be set to the name of this driver.
@@ -289,6 +301,8 @@ struct i2c_driver {
 	int (*detect)(struct i2c_client *client, struct i2c_board_info *info);
 	const unsigned short *address_list;
 	struct list_head clients;
+
+	unsigned int flags;
 };
 #define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)
 
-- 
2.20.1


  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-26 11:54 [PATCH v6 0/6] Support running driver's probe for a device powered off Sakari Ailus
2020-08-26 11:54 ` Sakari Ailus [this message]
2020-08-28  8:38   ` [PATCH v6 1/6] i2c: Allow an ACPI driver to manage the device's power state during probe Wolfram Sang
2020-08-31  8:23     ` Sakari Ailus
2020-08-31  9:31       ` Wolfram Sang
2020-08-31  9:54         ` Sakari Ailus
2020-08-31 10:00   ` Wolfram Sang
2020-08-31 17:05     ` Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 2/6] ACPI: Add a convenience function to tell a device is in low power state Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 3/6] ov5670: Support probe whilst the device is in a " Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 4/6] media: i2c: imx319: Support probe while the device is off Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 5/6] at24: Support probing while off Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 6/6] Documentation: ACPI: Document allow-low-power-probe _DSD property Sakari Ailus
2020-08-26 18:06   ` Randy Dunlap
2020-08-27 13:28     ` Sakari Ailus
2020-09-01 20:28       ` Sakari Ailus

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