Re: [RFC v4 01/14] regulator: of: Add helper for getting all supplies

[Krzysztof Kozlowski <k.kozlowski@samsung.com>]

On 06/09/2016 12:29 PM, Mark Brown wrote:
> On Thu, Jun 09, 2016 at 11:44:18AM +0200, Krzysztof Kozlowski wrote:
>> Few drivers have a need of getting regulator supplies without knowing
>> their names:
>> 1. The Simple Framebuffer driver works on setup provided by bootloader
>>    (outside of scope of kernel);
>> 2. Generic power sequence driver may be attached to any device node.
>>
>> Add a Device Tree helper for parsing "-supply" properties and returning
>> allocated bulk regulator consumers.
> 
> I'm still very concerned that this is just an invitation to people to
> write half baked regulator consumers and half baked DTs to go along with
> it, making it a standard API that doesn't have big red flags on it that
> will flag up when "normal" drivers use it is not good.  Right now this
> just looks like a standard API and people are going to just start using
> it.  If we are going to do this perhaps we need a separate header or
> something to help flag this up.

No problem, I can move it to a special header.  Actually, if you dislike
this as an API, it does not have to be in header at all.  I can just
duplicate the simplefb code.

> In the case of power sequences I'd expect the sequences to perform
> operations on named supplies - the core shouldn't know what the supplies
> are but the thing specifying the sequence should.

Hm, so maybe passing names like:

usb3503@08 {
	reset-gpios = <&gpx3 5 GPIO_ACTIVE_HIGH>;
	initial-mode = <1>;
	vdd-supply = <&buck8_reg>;
	foo-supply = <&buck9_reg>;

        power-sequence;
	power-sequence-supplies = "vdd", "foo";
};

but this is getting against initial idea of not adding any
power-sequence properties.

> 
>>  drivers/regulator/of_regulator.c       | 86 ++++++++++++++++++++++++++++++++++
>>  include/linux/regulator/of_regulator.h | 13 +++++
>>  2 files changed, 99 insertions(+)
> 
> The external interface shouldn't be DT specific, the Intel people are
> busy importing all of DT into ACPI so they'll doubtless want an ACPI
> version.

Sure, I'll add it if this approach is acceptable.  At this moment this
is not necessary to show my idea so I prefer to avoid doing work which
might be discarded very fast by review.

Thanks for feedback!

Best regards,
Krzysztof