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

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Message-ID: <CAPDyKFpMSwXG0e1Q38wMwBocXgMb4_v9y=1kNeNi6t0GXDGN2A@mail.gmail.com>
Date:	Wed, 5 Mar 2014 08:22:48 +0100
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Tomasz Figa <tomasz.figa@...il.com>
Cc:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-samsung-soc@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, devicetree@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
	Russell King <linux@....linux.org.uk>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Kumar Gala <galak@...eaurora.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Mark Rutland <mark.rutland@....com>,
	Pawel Moll <pawel.moll@....com>,
	Rob Herring <robh+dt@...nel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Tomasz Figa <t.figa@...sung.com>,
	Mark Brown <broonie@...nel.org>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH v2 02/11] drivercore: Bind/unbind power domain on probe/remove

On 3 March 2014 17:02, Tomasz Figa <tomasz.figa@...il.com> 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@...il.com>

This definitely makes sense to me!

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

> ---
>  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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