Re: [PATCH v2 02/11] drivercore: Bind/unbind power domain on probe/remove

[Ulf Hansson]

On 3 March 2014 17:02, Tomasz Figa <tomasz.figa@xxxxxxxxx> wrote:
> On a number of platforms, devices are part of controllable power
> domains, which need to be enabled before such devices can be accessed
> and may be powered down when the device is idle to save some power.
> This means that on systems that support power domain control using
> generic power domains subsystem, it is necessary to add device to its
> power domain before binding a driver to it and remove it from its power
> domain after its driver is unbound to make sure that an unused device
> does not affect power domain state.
>
> Since this is not limited to particular busses and specific
> archs/platforms, it is more convenient to do the above directly in
> driver core, just as done with pinctrl default configuration. This patch
> adds necessary code to really_probe() and __device_release_driver() to
> achieve this and maintain consistent stack-like ordering of operations
> happening when binding and unbinding a driver.
>
> Signed-off-by: Tomasz Figa <tomasz.figa@xxxxxxxxx>

This definitely makes sense to me!

Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>

> ---
>  drivers/base/dd.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 0605176..78e5b36 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -23,6 +23,7 @@
>  #include <linux/kthread.h>
>  #include <linux/wait.h>
>  #include <linux/async.h>
> +#include <linux/pm_domain.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/pinctrl/devinfo.h>
>
> @@ -273,6 +274,11 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>
>         dev->driver = drv;
>
> +       /* If using genpd, bind power domain now before probing */
> +       ret = genpd_bind_domain(dev);
> +       if (ret)
> +               goto probe_failed;
> +
>         /* If using pinctrl, bind pins now before probing */
>         ret = pinctrl_bind_pins(dev);
>         if (ret)
> @@ -303,6 +309,7 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>  probe_failed:
>         devres_release_all(dev);
>         driver_sysfs_remove(dev);
> +       genpd_unbind_domain(dev);
>         dev->driver = NULL;
>         dev_set_drvdata(dev, NULL);
>
> @@ -513,7 +520,7 @@ static void __device_release_driver(struct device *dev)
>                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
>                                                      BUS_NOTIFY_UNBOUND_DRIVER,
>                                                      dev);
> -
> +               genpd_unbind_domain(dev);
>         }
>  }
>
> --
> 1.9.0
>
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