[PATCH 02/24] drivercore: Bind/unbind power domain on probe/remove

Ulf Hansson ulf.hansson at linaro.org
Tue Jun 10 05:53:26 PDT 2014

On 10 June 2014 14:11, Rafael J. Wysocki <rafael at kernel.org> wrote:
> On Tue, Jun 10, 2014 at 12:51 PM, Ulf Hansson <ulf.hansson at linaro.org> wrote:
>> From: Tomasz Figa <t.figa at samsung.com>
>> 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,
> Actually, this isn't correrct.  It is limited to the platforms that
> use Device Trees now.

Correct, we should update the commit message/docs.

> Moreover, it is not consistent with the way we add devices to the ACPI PM
> domain, which is the ACPI counterpart of this.

I am not sure why you think consistency for ACPI is important here.
ACPI PM will still be able to handle it's domain/device registering as
before. There are even other pm_domains that don't use genpd which
need to handle this themselves.

Or are you saying that you prefer bus notifiers in favour of making
use of the driver core for this matter? Shouldn't the driver core
handle most of the common things for a device driver? Let's compare
how the pinctrls are being managed in the driver core, for example.

Kind regards
Ulf Hansson

> Rafael

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