| Message ID | 1380632982-10709-1-git-send-email-mika.westerberg@linux.intel.com |
|---|---|
| State | Deferred |
| Headers | show |
On Tuesday, October 01, 2013 04:09:42 PM Mika Westerberg wrote: > The ACPI specification requires the parent device to be powered on before > any of its children. It can be only powered off when all the children are > already off. > > Currently whenever there is no I2C traffic going on, the I2C controller > driver can put the device into low power state transparently to its > children (the I2C client devices). This violates the ACPI specification > because now the parent device is in lower power state than its children. > > In order to keep ACPI happy we enable runtime PM for the I2C adapter device > if we find out that the I2C controller was in fact an ACPI device. In > addition to that we attach the I2C client devices to the ACPI power domain > and make sure that they are powered on when the driver ->probe() is called. > > Non-ACPI devices are not affected by this change. > > This patch is based on the work by Aaron Lu and Lv Zheng. > > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > Changes to v3: > * Check only client ACPI_HANDLE(). > * Fixed bug where we attach the device to ACPI power domain multiple > times. > * Functions are renamed to _get_attach/_put_attach to make it clear that > we do attach/detach as well. > > drivers/i2c/i2c-core.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 46 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index 29d3f04..e289b1d 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -236,6 +236,27 @@ int i2c_recover_bus(struct i2c_adapter *adap) > return adap->bus_recovery_info->recover_bus(adap); > } > > +static void acpi_i2c_device_pm_get_attach(struct i2c_client *client, > + bool attach) > +{ > + if (ACPI_HANDLE(&client->dev)) { > + /* Make sure the adapter is active */ > + pm_runtime_get_sync(&client->adapter->dev); > + if (attach) > + acpi_dev_pm_attach(&client->dev, true); > + } > +} > + > +static void acpi_i2c_device_pm_put_detach(struct i2c_client *client, > + bool detach) > +{ > + if (ACPI_HANDLE(&client->dev)) { > + if (detach) > + acpi_dev_pm_detach(&client->dev, true); > + pm_runtime_put(&client->adapter->dev); > + } > +} > + > static int i2c_device_probe(struct device *dev) > { > struct i2c_client *client = i2c_verify_client(dev); > @@ -254,11 +275,15 @@ static int i2c_device_probe(struct device *dev) > client->flags & I2C_CLIENT_WAKE); > dev_dbg(dev, "probe\n"); > > + acpi_i2c_device_pm_get_attach(client, true); > + > status = driver->probe(client, i2c_match_id(driver->id_table, client)); > if (status) { > client->driver = NULL; > i2c_set_clientdata(client, NULL); > } > + > + acpi_i2c_device_pm_put_detach(client, !!status); > return status; > } > > @@ -271,6 +296,8 @@ static int i2c_device_remove(struct device *dev) > if (!client || !dev->driver) > return 0; > > + acpi_i2c_device_pm_get_attach(client, false); > + > driver = to_i2c_driver(dev->driver); > if (driver->remove) { > dev_dbg(dev, "remove\n"); > @@ -283,6 +310,8 @@ static int i2c_device_remove(struct device *dev) > client->driver = NULL; > i2c_set_clientdata(client, NULL); > } > + > + acpi_i2c_device_pm_put_detach(client, true); > return status; > } > > @@ -294,8 +323,11 @@ 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) { > + acpi_i2c_device_pm_get_attach(client, false); > driver->shutdown(client); > + acpi_i2c_device_pm_put_detach(client, false); > + } > } > > #ifdef CONFIG_PM_SLEEP > @@ -1263,6 +1295,16 @@ exit_recovery: > bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter); > mutex_unlock(&core_lock); > > + /* > + * For ACPI enumerated controllers we must make sure that the > + * controller is powered on before its children. Runtime PM handles > + * this for us once we have enabled it for the adapter device. > + */ > + if (ACPI_HANDLE(adap->dev.parent)) { > + pm_runtime_no_callbacks(&adap->dev); > + pm_runtime_enable(&adap->dev); > + } > + > return 0; > > out_list: > @@ -1427,6 +1469,9 @@ void i2c_del_adapter(struct i2c_adapter *adap) > return; > } > > + if (ACPI_HANDLE(adap->dev.parent)) > + pm_runtime_disable(&adap->dev); > + > /* Tell drivers about this removal */ > mutex_lock(&core_lock); > bus_for_each_drv(&i2c_bus_type, NULL, adap, >
On Tue, Oct 01, 2013 at 04:09:42PM +0300, Mika Westerberg wrote: > The ACPI specification requires the parent device to be powered on before > any of its children. It can be only powered off when all the children are > already off. > > Currently whenever there is no I2C traffic going on, the I2C controller > driver can put the device into low power state transparently to its > children (the I2C client devices). This violates the ACPI specification > because now the parent device is in lower power state than its children. > > In order to keep ACPI happy we enable runtime PM for the I2C adapter device > if we find out that the I2C controller was in fact an ACPI device. In > addition to that we attach the I2C client devices to the ACPI power domain > and make sure that they are powered on when the driver ->probe() is called. It looks like Windows actually powers the I2C controller off independently of the I2C client power state. We should probably do the same in Linux even though it is not following what the ACPI spec says (but makes sense with serial buses like I2C and SPI). Wolfram, please don't apply this patch - we are going to do one more iteration but this time we only attach devices to the ACPI power domain and leave runtime PM alone. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sat, Oct 05, 2013 at 11:09:01AM +0300, Mika Westerberg wrote: > It looks like Windows actually powers the I2C controller off independently > of the I2C client power state. We should probably do the same in Linux even > though it is not following what the ACPI spec says (but makes sense with > serial buses like I2C and SPI). Sounds like it's probably worth going to the effort of getting the spec amended...
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 29d3f04..e289b1d 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -236,6 +236,27 @@ int i2c_recover_bus(struct i2c_adapter *adap) return adap->bus_recovery_info->recover_bus(adap); } +static void acpi_i2c_device_pm_get_attach(struct i2c_client *client, + bool attach) +{ + if (ACPI_HANDLE(&client->dev)) { + /* Make sure the adapter is active */ + pm_runtime_get_sync(&client->adapter->dev); + if (attach) + acpi_dev_pm_attach(&client->dev, true); + } +} + +static void acpi_i2c_device_pm_put_detach(struct i2c_client *client, + bool detach) +{ + if (ACPI_HANDLE(&client->dev)) { + if (detach) + acpi_dev_pm_detach(&client->dev, true); + pm_runtime_put(&client->adapter->dev); + } +} + static int i2c_device_probe(struct device *dev) { struct i2c_client *client = i2c_verify_client(dev); @@ -254,11 +275,15 @@ static int i2c_device_probe(struct device *dev) client->flags & I2C_CLIENT_WAKE); dev_dbg(dev, "probe\n"); + acpi_i2c_device_pm_get_attach(client, true); + status = driver->probe(client, i2c_match_id(driver->id_table, client)); if (status) { client->driver = NULL; i2c_set_clientdata(client, NULL); } + + acpi_i2c_device_pm_put_detach(client, !!status); return status; } @@ -271,6 +296,8 @@ static int i2c_device_remove(struct device *dev) if (!client || !dev->driver) return 0; + acpi_i2c_device_pm_get_attach(client, false); + driver = to_i2c_driver(dev->driver); if (driver->remove) { dev_dbg(dev, "remove\n"); @@ -283,6 +310,8 @@ static int i2c_device_remove(struct device *dev) client->driver = NULL; i2c_set_clientdata(client, NULL); } + + acpi_i2c_device_pm_put_detach(client, true); return status; } @@ -294,8 +323,11 @@ 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) { + acpi_i2c_device_pm_get_attach(client, false); driver->shutdown(client); + acpi_i2c_device_pm_put_detach(client, false); + } } #ifdef CONFIG_PM_SLEEP @@ -1263,6 +1295,16 @@ exit_recovery: bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter); mutex_unlock(&core_lock); + /* + * For ACPI enumerated controllers we must make sure that the + * controller is powered on before its children. Runtime PM handles + * this for us once we have enabled it for the adapter device. + */ + if (ACPI_HANDLE(adap->dev.parent)) { + pm_runtime_no_callbacks(&adap->dev); + pm_runtime_enable(&adap->dev); + } + return 0; out_list: @@ -1427,6 +1469,9 @@ void i2c_del_adapter(struct i2c_adapter *adap) return; } + if (ACPI_HANDLE(adap->dev.parent)) + pm_runtime_disable(&adap->dev); + /* Tell drivers about this removal */ mutex_lock(&core_lock); bus_for_each_drv(&i2c_bus_type, NULL, adap,
The ACPI specification requires the parent device to be powered on before any of its children. It can be only powered off when all the children are already off. Currently whenever there is no I2C traffic going on, the I2C controller driver can put the device into low power state transparently to its children (the I2C client devices). This violates the ACPI specification because now the parent device is in lower power state than its children. In order to keep ACPI happy we enable runtime PM for the I2C adapter device if we find out that the I2C controller was in fact an ACPI device. In addition to that we attach the I2C client devices to the ACPI power domain and make sure that they are powered on when the driver ->probe() is called. Non-ACPI devices are not affected by this change. This patch is based on the work by Aaron Lu and Lv Zheng. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> --- Changes to v3: * Check only client ACPI_HANDLE(). * Fixed bug where we attach the device to ACPI power domain multiple times. * Functions are renamed to _get_attach/_put_attach to make it clear that we do attach/detach as well. drivers/i2c/i2c-core.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 46 insertions(+), 1 deletion(-)