Re: [RFC PATCH 1/2] i2c: prepare runtime PM support for I2C client devices
On Wed, Aug 28, 2013 at 11:38:58AM +0200, Wolfram Sang wrote: > On Tue, Aug 20, 2013 at 05:03:35PM +0300, Mika Westerberg wrote: > > From: Aaron Lu > > > > This patch adds runtime PM support for the I2C bus in a similar way that > > has been done for PCI bus already. This means that the I2C bus core > > prepares runtime PM for a client device just before a driver is about to be > > bound to it. Devices that are not bound to any driver are not prepared for > > runtime PM. > > > > In order to take advantage of this runtime PM support, the client device > > driver needs drop the device runtime PM reference count by calling > > pm_runtime_put() in its ->probe() callback and possibly implement rest of > > the runtime PM callbacks. > > > > However, this does not yet make runtime PM happen for the device, it has to > > be explicitly allowed from userspace per each I2C client device. The > > reason for this is that things like HID over I2C might not work as smoothly > > when runtime PM is active. So we leave it to the user to balance between > > performance and power efficiency. > > > > User can allow runtime PM for the client device by running: > > > > # echo auto > /sys/bus/i2c/devices//power/control > > > > and it can be forbidden again by: > > > > # echo on > /sys/bus/i2c/devices//power/control > > > > Status of the device can be monitored by reading files under the device > > power directory. > > > > If the driver doesn't support runtime PM (like most of the existing I2C > > client drivers), the device in question is regarded as being runtime PM > > active and powered on. > > > > The patch adds also runtime PM support for the adapter device because it is > > needed to be able to runtime power manage the I2C controller device. The > > adapter device is handled along with the I2C controller device (it uses > > pm_runtime_no_callbacks()). > > > > Signed-off-by: Aaron Lu > > Signed-off-by: Mika Westerberg > > CCing ALKML. Would appreciate comments/tags from the runtime-PM users of > the ARM world. Any comments on this? I can resend the whole series with ALKML included if that helps. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [RFC PATCH 1/2] i2c: prepare runtime PM support for I2C client devices
On Wed, Aug 28, 2013 at 11:38:58AM +0200, Wolfram Sang wrote: On Tue, Aug 20, 2013 at 05:03:35PM +0300, Mika Westerberg wrote: From: Aaron Lu aaron...@intel.com This patch adds runtime PM support for the I2C bus in a similar way that has been done for PCI bus already. This means that the I2C bus core prepares runtime PM for a client device just before a driver is about to be bound to it. Devices that are not bound to any driver are not prepared for runtime PM. In order to take advantage of this runtime PM support, the client device driver needs drop the device runtime PM reference count by calling pm_runtime_put() in its -probe() callback and possibly implement rest of the runtime PM callbacks. However, this does not yet make runtime PM happen for the device, it has to be explicitly allowed from userspace per each I2C client device. The reason for this is that things like HID over I2C might not work as smoothly when runtime PM is active. So we leave it to the user to balance between performance and power efficiency. User can allow runtime PM for the client device by running: # echo auto /sys/bus/i2c/devices/device/power/control and it can be forbidden again by: # echo on /sys/bus/i2c/devices/device/power/control Status of the device can be monitored by reading files under the device power directory. If the driver doesn't support runtime PM (like most of the existing I2C client drivers), the device in question is regarded as being runtime PM active and powered on. The patch adds also runtime PM support for the adapter device because it is needed to be able to runtime power manage the I2C controller device. The adapter device is handled along with the I2C controller device (it uses pm_runtime_no_callbacks()). Signed-off-by: Aaron Lu aaron...@intel.com Signed-off-by: Mika Westerberg mika.westerb...@linux.intel.com CCing ALKML. Would appreciate comments/tags from the runtime-PM users of the ARM world. Any comments on this? I can resend the whole series with ALKML included if that helps. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [RFC PATCH 1/2] i2c: prepare runtime PM support for I2C client devices
On Tue, Aug 20, 2013 at 05:03:35PM +0300, Mika Westerberg wrote:
> From: Aaron Lu
>
> This patch adds runtime PM support for the I2C bus in a similar way that
> has been done for PCI bus already. This means that the I2C bus core
> prepares runtime PM for a client device just before a driver is about to be
> bound to it. Devices that are not bound to any driver are not prepared for
> runtime PM.
>
> In order to take advantage of this runtime PM support, the client device
> driver needs drop the device runtime PM reference count by calling
> pm_runtime_put() in its ->probe() callback and possibly implement rest of
> the runtime PM callbacks.
>
> However, this does not yet make runtime PM happen for the device, it has to
> be explicitly allowed from userspace per each I2C client device. The
> reason for this is that things like HID over I2C might not work as smoothly
> when runtime PM is active. So we leave it to the user to balance between
> performance and power efficiency.
>
> User can allow runtime PM for the client device by running:
>
> # echo auto > /sys/bus/i2c/devices//power/control
>
> and it can be forbidden again by:
>
> # echo on > /sys/bus/i2c/devices//power/control
>
> Status of the device can be monitored by reading files under the device
> power directory.
>
> If the driver doesn't support runtime PM (like most of the existing I2C
> client drivers), the device in question is regarded as being runtime PM
> active and powered on.
>
> The patch adds also runtime PM support for the adapter device because it is
> needed to be able to runtime power manage the I2C controller device. The
> adapter device is handled along with the I2C controller device (it uses
> pm_runtime_no_callbacks()).
>
> Signed-off-by: Aaron Lu
> Signed-off-by: Mika Westerberg
CCing ALKML. Would appreciate comments/tags from the runtime-PM users of
the ARM world.
> ---
> drivers/i2c/i2c-core.c | 48 +++-
> 1 file changed, 47 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index 3d44292..8fad5ac 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -254,11 +254,34 @@ static int i2c_device_probe(struct device *dev)
> client->flags & I2C_CLIENT_WAKE);
> dev_dbg(dev, "probe\n");
>
> + /* Make sure the adapter is active */
> + pm_runtime_get_sync(>adapter->dev);
> +
> + /*
> + * Enable runtime PM for the client device. If the client wants to
> + * participate on runtime PM it should call pm_runtime_put() in its
> + * probe() callback.
> + *
> + * User still needs to allow the PM runtime before it can actually
> + * happen.
> + */
> + pm_runtime_forbid(>dev);
> + pm_runtime_get_noresume(>dev);
> + pm_runtime_set_active(>dev);
> + pm_runtime_enable(>dev);
> +
> status = driver->probe(client, i2c_match_id(driver->id_table, client));
> if (status) {
> client->driver = NULL;
> i2c_set_clientdata(client, NULL);
> +
> + pm_runtime_disable(>dev);
> + pm_runtime_set_suspended(>dev);
> + pm_runtime_put_noidle(>dev);
> }
> +
> + pm_runtime_put(>adapter->dev);
> +
> return status;
> }
>
> @@ -271,6 +294,8 @@ static int i2c_device_remove(struct device *dev)
> if (!client || !dev->driver)
> return 0;
>
> + pm_runtime_get_sync(>adapter->dev);
> +
> driver = to_i2c_driver(dev->driver);
> if (driver->remove) {
> dev_dbg(dev, "remove\n");
> @@ -283,6 +308,13 @@ static int i2c_device_remove(struct device *dev)
> client->driver = NULL;
> i2c_set_clientdata(client, NULL);
> }
> +
> + /* Undo the runtime PM done in i2c_probe() */
> + pm_runtime_disable(>dev);
> + pm_runtime_set_suspended(>dev);
> + pm_runtime_put_noidle(>dev);
> +
> + pm_runtime_put(>adapter->dev);
> return status;
> }
>
> @@ -294,8 +326,11 @@ static void i2c_device_shutdown(struct device *dev)
> if (!client || !dev->driver)
> return;
> driver = to_i2c_driver(dev->driver);
> - if (driver->shutdown)
> + if (driver->shutdown) {
> + pm_runtime_get_sync(>adapter->dev);
> driver->shutdown(client);
> + pm_runtime_put(>adapter->dev);
> + }
> }
>
> #ifdef CONFIG_PM_SLEEP
> @@ -1263,6 +1298,15 @@ exit_recovery:
> bus_for_each_drv(_bus_type, NULL, adap, __process_new_adapter);
> mutex_unlock(_lock);
>
> + /*
> + * Make sure the adapter runtime PM follows the parent device (the
> + * host controller) so that we can suspend it once there aren't any
> + * active clients anymore.
> + */
> + pm_runtime_set_active(>dev);
> + pm_runtime_no_callbacks(>dev);
> + pm_runtime_enable(>dev);
> +
> return 0;
>
> out_list:
Re: [RFC PATCH 1/2] i2c: prepare runtime PM support for I2C client devices
On Tue, Aug 20, 2013 at 05:03:35PM +0300, Mika Westerberg wrote:
From: Aaron Lu aaron...@intel.com
This patch adds runtime PM support for the I2C bus in a similar way that
has been done for PCI bus already. This means that the I2C bus core
prepares runtime PM for a client device just before a driver is about to be
bound to it. Devices that are not bound to any driver are not prepared for
runtime PM.
In order to take advantage of this runtime PM support, the client device
driver needs drop the device runtime PM reference count by calling
pm_runtime_put() in its -probe() callback and possibly implement rest of
the runtime PM callbacks.
However, this does not yet make runtime PM happen for the device, it has to
be explicitly allowed from userspace per each I2C client device. The
reason for this is that things like HID over I2C might not work as smoothly
when runtime PM is active. So we leave it to the user to balance between
performance and power efficiency.
User can allow runtime PM for the client device by running:
# echo auto /sys/bus/i2c/devices/device/power/control
and it can be forbidden again by:
# echo on /sys/bus/i2c/devices/device/power/control
Status of the device can be monitored by reading files under the device
power directory.
If the driver doesn't support runtime PM (like most of the existing I2C
client drivers), the device in question is regarded as being runtime PM
active and powered on.
The patch adds also runtime PM support for the adapter device because it is
needed to be able to runtime power manage the I2C controller device. The
adapter device is handled along with the I2C controller device (it uses
pm_runtime_no_callbacks()).
Signed-off-by: Aaron Lu aaron...@intel.com
Signed-off-by: Mika Westerberg mika.westerb...@linux.intel.com
CCing ALKML. Would appreciate comments/tags from the runtime-PM users of
the ARM world.
---
drivers/i2c/i2c-core.c | 48 +++-
1 file changed, 47 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 3d44292..8fad5ac 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -254,11 +254,34 @@ static int i2c_device_probe(struct device *dev)
client-flags I2C_CLIENT_WAKE);
dev_dbg(dev, probe\n);
+ /* Make sure the adapter is active */
+ pm_runtime_get_sync(client-adapter-dev);
+
+ /*
+ * Enable runtime PM for the client device. If the client wants to
+ * participate on runtime PM it should call pm_runtime_put() in its
+ * probe() callback.
+ *
+ * User still needs to allow the PM runtime before it can actually
+ * happen.
+ */
+ pm_runtime_forbid(client-dev);
+ pm_runtime_get_noresume(client-dev);
+ pm_runtime_set_active(client-dev);
+ pm_runtime_enable(client-dev);
+
status = driver-probe(client, i2c_match_id(driver-id_table, client));
if (status) {
client-driver = NULL;
i2c_set_clientdata(client, NULL);
+
+ pm_runtime_disable(client-dev);
+ pm_runtime_set_suspended(client-dev);
+ pm_runtime_put_noidle(client-dev);
}
+
+ pm_runtime_put(client-adapter-dev);
+
return status;
}
@@ -271,6 +294,8 @@ static int i2c_device_remove(struct device *dev)
if (!client || !dev-driver)
return 0;
+ pm_runtime_get_sync(client-adapter-dev);
+
driver = to_i2c_driver(dev-driver);
if (driver-remove) {
dev_dbg(dev, remove\n);
@@ -283,6 +308,13 @@ static int i2c_device_remove(struct device *dev)
client-driver = NULL;
i2c_set_clientdata(client, NULL);
}
+
+ /* Undo the runtime PM done in i2c_probe() */
+ pm_runtime_disable(client-dev);
+ pm_runtime_set_suspended(client-dev);
+ pm_runtime_put_noidle(client-dev);
+
+ pm_runtime_put(client-adapter-dev);
return status;
}
@@ -294,8 +326,11 @@ static void i2c_device_shutdown(struct device *dev)
if (!client || !dev-driver)
return;
driver = to_i2c_driver(dev-driver);
- if (driver-shutdown)
+ if (driver-shutdown) {
+ pm_runtime_get_sync(client-adapter-dev);
driver-shutdown(client);
+ pm_runtime_put(client-adapter-dev);
+ }
}
#ifdef CONFIG_PM_SLEEP
@@ -1263,6 +1298,15 @@ exit_recovery:
bus_for_each_drv(i2c_bus_type, NULL, adap, __process_new_adapter);
mutex_unlock(core_lock);
+ /*
+ * Make sure the adapter runtime PM follows the parent device (the
+ * host controller) so that we can suspend it once there aren't any
+ * active clients anymore.
+ */
+ pm_runtime_set_active(adap-dev);
+ pm_runtime_no_callbacks(adap-dev);
+ pm_runtime_enable(adap-dev);
+
Re: [RFC PATCH 1/2] i2c: prepare runtime PM support for I2C client devices
On Tuesday, August 20, 2013 05:03:35 PM Mika Westerberg wrote:
> From: Aaron Lu
>
> This patch adds runtime PM support for the I2C bus in a similar way that
> has been done for PCI bus already. This means that the I2C bus core
> prepares runtime PM for a client device just before a driver is about to be
> bound to it. Devices that are not bound to any driver are not prepared for
> runtime PM.
>
> In order to take advantage of this runtime PM support, the client device
> driver needs drop the device runtime PM reference count by calling
> pm_runtime_put() in its ->probe() callback and possibly implement rest of
> the runtime PM callbacks.
>
> However, this does not yet make runtime PM happen for the device, it has to
> be explicitly allowed from userspace per each I2C client device. The
> reason for this is that things like HID over I2C might not work as smoothly
> when runtime PM is active. So we leave it to the user to balance between
> performance and power efficiency.
>
> User can allow runtime PM for the client device by running:
>
> # echo auto > /sys/bus/i2c/devices//power/control
>
> and it can be forbidden again by:
>
> # echo on > /sys/bus/i2c/devices//power/control
>
> Status of the device can be monitored by reading files under the device
> power directory.
>
> If the driver doesn't support runtime PM (like most of the existing I2C
> client drivers), the device in question is regarded as being runtime PM
> active and powered on.
>
> The patch adds also runtime PM support for the adapter device because it is
> needed to be able to runtime power manage the I2C controller device. The
> adapter device is handled along with the I2C controller device (it uses
> pm_runtime_no_callbacks()).
>
> Signed-off-by: Aaron Lu
> Signed-off-by: Mika Westerberg
Acked-by: Rafael J. Wysocki
> ---
> drivers/i2c/i2c-core.c | 48 +++-
> 1 file changed, 47 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index 3d44292..8fad5ac 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -254,11 +254,34 @@ static int i2c_device_probe(struct device *dev)
> client->flags & I2C_CLIENT_WAKE);
> dev_dbg(dev, "probe\n");
>
> + /* Make sure the adapter is active */
> + pm_runtime_get_sync(>adapter->dev);
> +
> + /*
> + * Enable runtime PM for the client device. If the client wants to
> + * participate on runtime PM it should call pm_runtime_put() in its
> + * probe() callback.
> + *
> + * User still needs to allow the PM runtime before it can actually
> + * happen.
> + */
> + pm_runtime_forbid(>dev);
> + pm_runtime_get_noresume(>dev);
> + pm_runtime_set_active(>dev);
> + pm_runtime_enable(>dev);
> +
> status = driver->probe(client, i2c_match_id(driver->id_table, client));
> if (status) {
> client->driver = NULL;
> i2c_set_clientdata(client, NULL);
> +
> + pm_runtime_disable(>dev);
> + pm_runtime_set_suspended(>dev);
> + pm_runtime_put_noidle(>dev);
> }
> +
> + pm_runtime_put(>adapter->dev);
> +
> return status;
> }
>
> @@ -271,6 +294,8 @@ static int i2c_device_remove(struct device *dev)
> if (!client || !dev->driver)
> return 0;
>
> + pm_runtime_get_sync(>adapter->dev);
> +
> driver = to_i2c_driver(dev->driver);
> if (driver->remove) {
> dev_dbg(dev, "remove\n");
> @@ -283,6 +308,13 @@ static int i2c_device_remove(struct device *dev)
> client->driver = NULL;
> i2c_set_clientdata(client, NULL);
> }
> +
> + /* Undo the runtime PM done in i2c_probe() */
> + pm_runtime_disable(>dev);
> + pm_runtime_set_suspended(>dev);
> + pm_runtime_put_noidle(>dev);
> +
> + pm_runtime_put(>adapter->dev);
> return status;
> }
>
> @@ -294,8 +326,11 @@ static void i2c_device_shutdown(struct device *dev)
> if (!client || !dev->driver)
> return;
> driver = to_i2c_driver(dev->driver);
> - if (driver->shutdown)
> + if (driver->shutdown) {
> + pm_runtime_get_sync(>adapter->dev);
> driver->shutdown(client);
> + pm_runtime_put(>adapter->dev);
> + }
> }
>
> #ifdef CONFIG_PM_SLEEP
> @@ -1263,6 +1298,15 @@ exit_recovery:
> bus_for_each_drv(_bus_type, NULL, adap, __process_new_adapter);
> mutex_unlock(_lock);
>
> + /*
> + * Make sure the adapter runtime PM follows the parent device (the
> + * host controller) so that we can suspend it once there aren't any
> + * active clients anymore.
> + */
> + pm_runtime_set_active(>dev);
> + pm_runtime_no_callbacks(>dev);
> + pm_runtime_enable(>dev);
> +
> return 0;
>
> out_list:
> @@ -1427,6 +1471,8 @@ void i2c_del_adapter(struct
[RFC PATCH 1/2] i2c: prepare runtime PM support for I2C client devices
From: Aaron Lu
This patch adds runtime PM support for the I2C bus in a similar way that
has been done for PCI bus already. This means that the I2C bus core
prepares runtime PM for a client device just before a driver is about to be
bound to it. Devices that are not bound to any driver are not prepared for
runtime PM.
In order to take advantage of this runtime PM support, the client device
driver needs drop the device runtime PM reference count by calling
pm_runtime_put() in its ->probe() callback and possibly implement rest of
the runtime PM callbacks.
However, this does not yet make runtime PM happen for the device, it has to
be explicitly allowed from userspace per each I2C client device. The
reason for this is that things like HID over I2C might not work as smoothly
when runtime PM is active. So we leave it to the user to balance between
performance and power efficiency.
User can allow runtime PM for the client device by running:
# echo auto > /sys/bus/i2c/devices//power/control
and it can be forbidden again by:
# echo on > /sys/bus/i2c/devices//power/control
Status of the device can be monitored by reading files under the device
power directory.
If the driver doesn't support runtime PM (like most of the existing I2C
client drivers), the device in question is regarded as being runtime PM
active and powered on.
The patch adds also runtime PM support for the adapter device because it is
needed to be able to runtime power manage the I2C controller device. The
adapter device is handled along with the I2C controller device (it uses
pm_runtime_no_callbacks()).
Signed-off-by: Aaron Lu
Signed-off-by: Mika Westerberg
---
drivers/i2c/i2c-core.c | 48 +++-
1 file changed, 47 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 3d44292..8fad5ac 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -254,11 +254,34 @@ static int i2c_device_probe(struct device *dev)
client->flags & I2C_CLIENT_WAKE);
dev_dbg(dev, "probe\n");
+ /* Make sure the adapter is active */
+ pm_runtime_get_sync(>adapter->dev);
+
+ /*
+* Enable runtime PM for the client device. If the client wants to
+* participate on runtime PM it should call pm_runtime_put() in its
+* probe() callback.
+*
+* User still needs to allow the PM runtime before it can actually
+* happen.
+*/
+ pm_runtime_forbid(>dev);
+ pm_runtime_get_noresume(>dev);
+ pm_runtime_set_active(>dev);
+ pm_runtime_enable(>dev);
+
status = driver->probe(client, i2c_match_id(driver->id_table, client));
if (status) {
client->driver = NULL;
i2c_set_clientdata(client, NULL);
+
+ pm_runtime_disable(>dev);
+ pm_runtime_set_suspended(>dev);
+ pm_runtime_put_noidle(>dev);
}
+
+ pm_runtime_put(>adapter->dev);
+
return status;
}
@@ -271,6 +294,8 @@ static int i2c_device_remove(struct device *dev)
if (!client || !dev->driver)
return 0;
+ pm_runtime_get_sync(>adapter->dev);
+
driver = to_i2c_driver(dev->driver);
if (driver->remove) {
dev_dbg(dev, "remove\n");
@@ -283,6 +308,13 @@ static int i2c_device_remove(struct device *dev)
client->driver = NULL;
i2c_set_clientdata(client, NULL);
}
+
+ /* Undo the runtime PM done in i2c_probe() */
+ pm_runtime_disable(>dev);
+ pm_runtime_set_suspended(>dev);
+ pm_runtime_put_noidle(>dev);
+
+ pm_runtime_put(>adapter->dev);
return status;
}
@@ -294,8 +326,11 @@ static void i2c_device_shutdown(struct device *dev)
if (!client || !dev->driver)
return;
driver = to_i2c_driver(dev->driver);
- if (driver->shutdown)
+ if (driver->shutdown) {
+ pm_runtime_get_sync(>adapter->dev);
driver->shutdown(client);
+ pm_runtime_put(>adapter->dev);
+ }
}
#ifdef CONFIG_PM_SLEEP
@@ -1263,6 +1298,15 @@ exit_recovery:
bus_for_each_drv(_bus_type, NULL, adap, __process_new_adapter);
mutex_unlock(_lock);
+ /*
+* Make sure the adapter runtime PM follows the parent device (the
+* host controller) so that we can suspend it once there aren't any
+* active clients anymore.
+*/
+ pm_runtime_set_active(>dev);
+ pm_runtime_no_callbacks(>dev);
+ pm_runtime_enable(>dev);
+
return 0;
out_list:
@@ -1427,6 +1471,8 @@ void i2c_del_adapter(struct i2c_adapter *adap)
return;
}
+ pm_runtime_disable(>dev);
+
/* Tell drivers about this removal */
mutex_lock(_lock);
bus_for_each_drv(_bus_type, NULL, adap,
--
1.8.4.rc2
--
To unsubscribe from
[RFC PATCH 1/2] i2c: prepare runtime PM support for I2C client devices
From: Aaron Lu aaron...@intel.com
This patch adds runtime PM support for the I2C bus in a similar way that
has been done for PCI bus already. This means that the I2C bus core
prepares runtime PM for a client device just before a driver is about to be
bound to it. Devices that are not bound to any driver are not prepared for
runtime PM.
In order to take advantage of this runtime PM support, the client device
driver needs drop the device runtime PM reference count by calling
pm_runtime_put() in its -probe() callback and possibly implement rest of
the runtime PM callbacks.
However, this does not yet make runtime PM happen for the device, it has to
be explicitly allowed from userspace per each I2C client device. The
reason for this is that things like HID over I2C might not work as smoothly
when runtime PM is active. So we leave it to the user to balance between
performance and power efficiency.
User can allow runtime PM for the client device by running:
# echo auto /sys/bus/i2c/devices/device/power/control
and it can be forbidden again by:
# echo on /sys/bus/i2c/devices/device/power/control
Status of the device can be monitored by reading files under the device
power directory.
If the driver doesn't support runtime PM (like most of the existing I2C
client drivers), the device in question is regarded as being runtime PM
active and powered on.
The patch adds also runtime PM support for the adapter device because it is
needed to be able to runtime power manage the I2C controller device. The
adapter device is handled along with the I2C controller device (it uses
pm_runtime_no_callbacks()).
Signed-off-by: Aaron Lu aaron...@intel.com
Signed-off-by: Mika Westerberg mika.westerb...@linux.intel.com
---
drivers/i2c/i2c-core.c | 48 +++-
1 file changed, 47 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 3d44292..8fad5ac 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -254,11 +254,34 @@ static int i2c_device_probe(struct device *dev)
client-flags I2C_CLIENT_WAKE);
dev_dbg(dev, probe\n);
+ /* Make sure the adapter is active */
+ pm_runtime_get_sync(client-adapter-dev);
+
+ /*
+* Enable runtime PM for the client device. If the client wants to
+* participate on runtime PM it should call pm_runtime_put() in its
+* probe() callback.
+*
+* User still needs to allow the PM runtime before it can actually
+* happen.
+*/
+ pm_runtime_forbid(client-dev);
+ pm_runtime_get_noresume(client-dev);
+ pm_runtime_set_active(client-dev);
+ pm_runtime_enable(client-dev);
+
status = driver-probe(client, i2c_match_id(driver-id_table, client));
if (status) {
client-driver = NULL;
i2c_set_clientdata(client, NULL);
+
+ pm_runtime_disable(client-dev);
+ pm_runtime_set_suspended(client-dev);
+ pm_runtime_put_noidle(client-dev);
}
+
+ pm_runtime_put(client-adapter-dev);
+
return status;
}
@@ -271,6 +294,8 @@ static int i2c_device_remove(struct device *dev)
if (!client || !dev-driver)
return 0;
+ pm_runtime_get_sync(client-adapter-dev);
+
driver = to_i2c_driver(dev-driver);
if (driver-remove) {
dev_dbg(dev, remove\n);
@@ -283,6 +308,13 @@ static int i2c_device_remove(struct device *dev)
client-driver = NULL;
i2c_set_clientdata(client, NULL);
}
+
+ /* Undo the runtime PM done in i2c_probe() */
+ pm_runtime_disable(client-dev);
+ pm_runtime_set_suspended(client-dev);
+ pm_runtime_put_noidle(client-dev);
+
+ pm_runtime_put(client-adapter-dev);
return status;
}
@@ -294,8 +326,11 @@ static void i2c_device_shutdown(struct device *dev)
if (!client || !dev-driver)
return;
driver = to_i2c_driver(dev-driver);
- if (driver-shutdown)
+ if (driver-shutdown) {
+ pm_runtime_get_sync(client-adapter-dev);
driver-shutdown(client);
+ pm_runtime_put(client-adapter-dev);
+ }
}
#ifdef CONFIG_PM_SLEEP
@@ -1263,6 +1298,15 @@ exit_recovery:
bus_for_each_drv(i2c_bus_type, NULL, adap, __process_new_adapter);
mutex_unlock(core_lock);
+ /*
+* Make sure the adapter runtime PM follows the parent device (the
+* host controller) so that we can suspend it once there aren't any
+* active clients anymore.
+*/
+ pm_runtime_set_active(adap-dev);
+ pm_runtime_no_callbacks(adap-dev);
+ pm_runtime_enable(adap-dev);
+
return 0;
out_list:
@@ -1427,6 +1471,8 @@ void i2c_del_adapter(struct i2c_adapter *adap)
return;
}
+
Re: [RFC PATCH 1/2] i2c: prepare runtime PM support for I2C client devices
On Tuesday, August 20, 2013 05:03:35 PM Mika Westerberg wrote:
From: Aaron Lu aaron...@intel.com
This patch adds runtime PM support for the I2C bus in a similar way that
has been done for PCI bus already. This means that the I2C bus core
prepares runtime PM for a client device just before a driver is about to be
bound to it. Devices that are not bound to any driver are not prepared for
runtime PM.
In order to take advantage of this runtime PM support, the client device
driver needs drop the device runtime PM reference count by calling
pm_runtime_put() in its -probe() callback and possibly implement rest of
the runtime PM callbacks.
However, this does not yet make runtime PM happen for the device, it has to
be explicitly allowed from userspace per each I2C client device. The
reason for this is that things like HID over I2C might not work as smoothly
when runtime PM is active. So we leave it to the user to balance between
performance and power efficiency.
User can allow runtime PM for the client device by running:
# echo auto /sys/bus/i2c/devices/device/power/control
and it can be forbidden again by:
# echo on /sys/bus/i2c/devices/device/power/control
Status of the device can be monitored by reading files under the device
power directory.
If the driver doesn't support runtime PM (like most of the existing I2C
client drivers), the device in question is regarded as being runtime PM
active and powered on.
The patch adds also runtime PM support for the adapter device because it is
needed to be able to runtime power manage the I2C controller device. The
adapter device is handled along with the I2C controller device (it uses
pm_runtime_no_callbacks()).
Signed-off-by: Aaron Lu aaron...@intel.com
Signed-off-by: Mika Westerberg mika.westerb...@linux.intel.com
Acked-by: Rafael J. Wysocki rafael.j.wyso...@intel.com
---
drivers/i2c/i2c-core.c | 48 +++-
1 file changed, 47 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 3d44292..8fad5ac 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -254,11 +254,34 @@ static int i2c_device_probe(struct device *dev)
client-flags I2C_CLIENT_WAKE);
dev_dbg(dev, probe\n);
+ /* Make sure the adapter is active */
+ pm_runtime_get_sync(client-adapter-dev);
+
+ /*
+ * Enable runtime PM for the client device. If the client wants to
+ * participate on runtime PM it should call pm_runtime_put() in its
+ * probe() callback.
+ *
+ * User still needs to allow the PM runtime before it can actually
+ * happen.
+ */
+ pm_runtime_forbid(client-dev);
+ pm_runtime_get_noresume(client-dev);
+ pm_runtime_set_active(client-dev);
+ pm_runtime_enable(client-dev);
+
status = driver-probe(client, i2c_match_id(driver-id_table, client));
if (status) {
client-driver = NULL;
i2c_set_clientdata(client, NULL);
+
+ pm_runtime_disable(client-dev);
+ pm_runtime_set_suspended(client-dev);
+ pm_runtime_put_noidle(client-dev);
}
+
+ pm_runtime_put(client-adapter-dev);
+
return status;
}
@@ -271,6 +294,8 @@ static int i2c_device_remove(struct device *dev)
if (!client || !dev-driver)
return 0;
+ pm_runtime_get_sync(client-adapter-dev);
+
driver = to_i2c_driver(dev-driver);
if (driver-remove) {
dev_dbg(dev, remove\n);
@@ -283,6 +308,13 @@ static int i2c_device_remove(struct device *dev)
client-driver = NULL;
i2c_set_clientdata(client, NULL);
}
+
+ /* Undo the runtime PM done in i2c_probe() */
+ pm_runtime_disable(client-dev);
+ pm_runtime_set_suspended(client-dev);
+ pm_runtime_put_noidle(client-dev);
+
+ pm_runtime_put(client-adapter-dev);
return status;
}
@@ -294,8 +326,11 @@ static void i2c_device_shutdown(struct device *dev)
if (!client || !dev-driver)
return;
driver = to_i2c_driver(dev-driver);
- if (driver-shutdown)
+ if (driver-shutdown) {
+ pm_runtime_get_sync(client-adapter-dev);
driver-shutdown(client);
+ pm_runtime_put(client-adapter-dev);
+ }
}
#ifdef CONFIG_PM_SLEEP
@@ -1263,6 +1298,15 @@ exit_recovery:
bus_for_each_drv(i2c_bus_type, NULL, adap, __process_new_adapter);
mutex_unlock(core_lock);
+ /*
+ * Make sure the adapter runtime PM follows the parent device (the
+ * host controller) so that we can suspend it once there aren't any
+ * active clients anymore.
+ */
+ pm_runtime_set_active(adap-dev);
+ pm_runtime_no_callbacks(adap-dev);
+ pm_runtime_enable(adap-dev);
+
return 0;
out_list:
@@
