Re: [PATCH V4 1/9] PM / OPP: Allow OPP table to be used for power-domains
From: Sudeep Holla
Date: Wed May 03 2017 - 07:22:09 EST
On 30/04/17 13:49, Mark Brown wrote:
> On Thu, Apr 27, 2017 at 10:42:49AM +0100, Sudeep Holla wrote:
>> On 26/04/17 14:55, Mark Brown wrote:
>>> As I'm getting fed up of saying: if the values you are setting are not
>>> voltages and do not behave like voltages then the hardware should not be
>>> represented as a voltage regulator since if they are represented as
>>> voltage regulators things will expect to be able to control them as
>>> voltage regulators. This hardware is quite clearly providing OPPs
>>> directly, I would expect this to be handled in the OPP code somehow.
>> I agree with you that we need to be absolutely sure on what it actually
>> But as more and more platform are pushing such power controls to
>> dedicated M3 or similar processors, we need abstraction. Though we are
>> controlling hardware, we do so indirectly. Since there were discussions
>> around device tree representing hardware vs platform, I tend to think,
>> we are moving towards platform(something similar to ACPI).
> I don't think there's a meaningful hardware/platform distinction here -
> in terms of what DT is describing the platform bit is just what the
> hardware (the microcontrollers) happen to do,
Yes agreed. It's similar to PSCI or any other platform firmware IMO.
The question is how do we deal with such controls that needs to be done
via the firmware ? We generally plug-in to the existing framework in
Linux using the existing bindings. Most of the time, much simpler
bindings than the one that present complete hardware description.
> DT doesn't much care about that though.
No sure about that, may be doesn't care about the internals, but we need
to care about interface, no ?