Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> writes: > From: Aaron Lu <aaron.lu@xxxxxxxxx> > > 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. > > 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. But for existing drivers which already support runtime PM (at least 7 by a quick grep), they will be stuck runtime enabled and stop hitting low-power states after this patch. > 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.lu@xxxxxxxxx> > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > --- > drivers/i2c/i2c-core.c | 44 +++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 43 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index f32ca29..44374b4 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -248,11 +248,30 @@ 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. > + */ > + pm_runtime_get_noresume(&client->dev); > + pm_runtime_set_active(&client->dev); Why the set_active here? For hardware that is disabled/powered-off on startup, there will now be a mismatch between the hardware state an the RPM core state. Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
