Re: [PATCH v3 1/2] dt-bindings: clk: Introduce 'critical-clocks' property

[Stephen Boyd <sboyd@kernel.org>]

Quoting Marek Vasut (2022-06-15 14:55:17)
> On 6/15/22 22:10, Stephen Boyd wrote:
> > Quoting Marek Vasut (2022-05-17 16:59:18)
> >> diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt
> >> index f2ea53832ac63..d7f7afe2cbd0c 100644
> >> --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt
> >> +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt
> >> @@ -169,6 +169,22 @@ a shared clock is forbidden.
> >>   Configuration of common clocks, which affect multiple consumer devices can
> >>   be similarly specified in the clock provider node.
> >>   
> >> +==Critical clocks==
> >> +
> >> +Some platforms require some clocks to be always running, e.g. because those
> >> +clock supply devices which are not otherwise attached to the system. One
> >> +example is a system where the SoC serves as a crystal oscillator replacement
> >> +for a programmable logic device. The critical-clocks property of a clock
> >> +controller allows listing clock which must never be turned off.
> >> +
> >> +   clock-controller@a000f000 {
> >> +        compatible = "vendor,clk95;
> >> +        reg = <0xa000f000 0x1000>
> >> +        #clocks-cells = <1>;
> >> +        ...
> >> +        critical-clocks = <UART3_CLK>, <SPI5_CLK>;
> > 
> > Historically "critical" is overloaded in the clk framework. We should
> > avoid using that name. What does "critical" even mean?
> 
> It means those clock must not be turned off, but there is no consumer 
> described in DT.

So it means "always on".

> 
> > Instead I'd prefer "always-on-clocks" here, so we can indicate that
> > these clks should always be on. It would also parallel the property in
> > the regulator framework.
> 
> This property name is derived from protected-clock which you introduced. 
> I think it would be better to stay consistent within the clock framework 
> property names ?

protected-clocks is based on assigned-clocks. There isn't a
CLK_IS_PROTECTED flag. I'm not following your argument at all here,
sorry.