Re: [RFC 1/3] devfreq: dt-bindings: Document Exynos3250 devfreq driver

[Krzysztof Kozlowski]

On piÄ, 2014-12-05 at 16:53 +0000, Mark Rutland wrote:
> On Fri, Dec 05, 2014 at 04:46:26PM +0000, Krzysztof Kozlowski wrote:
> > Add documentation for bindings used by Exynos3250 devfreq driver.
> > 
> > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
> > ---
> >  .../bindings/arm/samsung/exynos3250-devfreq.txt    | 66 ++++++++++++++++++++++
> >  1 file changed, 66 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/arm/samsung/exynos3250-devfreq.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/arm/samsung/exynos3250-devfreq.txt b/Documentation/devicetree/bindings/arm/samsung/exynos3250-devfreq.txt
> > new file mode 100644
> > index 000000000000..047955e9e371
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/arm/samsung/exynos3250-devfreq.txt
> > @@ -0,0 +1,66 @@
> > +Samsung Exynos3250 devfreq driver
> 
> The binding should describe the hardware, not a particular driver of
> that hardware. Please write the binding (and its documentation) with
> that in mind, and drop references to the driver and "busfreq".
> 
> With an adequate binding we can probe the device and forward the
> information to relevant driver(s) as necessary.

OK

> 
> > +=================================
> > +
> > +The driver support changing frequencies and voltage for:
> > + - memory controller and bus,
> > + - peripheral buses (left and right).
> 
> 
> What do left and right mean in this context?

These are names for clock domains associated with buses between memory
controller and peripherals. They're called "leftbus" and "rightbus" in
documentation.

> 
> > +
> > +Memory controller and bus
> > +=========================
> > +Required properties:
> > + - compatible : should be "samsung,exynos3250-busfreq-mif"
> > + - reg : two sets (offset and length of the register) for PPMU registers
> > +	used by this devfreq driver
> > + - clock-names : one clock of name "dmc" to manage frequency
> > + - clocks : phandle and specifier for clock listed in clock-names property
> > + - vdd_mif-supply : phandle to MIF voltage regulator
> 
> s/_/-/ in property names please.

Sure.

> 
> > +
> > +Peripheral buses
> > +================
> > +Required properties:
> > + - compatible : should be "samsung,exynos3250-busfreq-int"
> 
> What does "int" mean here?

It is the name of power source (VDD_INT) and regulator supplying certain
power domains in SoC. However I have no clue what engineers meant by
this abbreviation.

> 
> > + - reg : two sets (offset and length of the register) for PPMU registers
> > +	used by this devfreq driver
> > + - clock-names : names for PPMU clocks and bus clocks to manage frequencies;
> > +	All following clock names (and corresponding phandles) must be
> > +	provided:
> > +	- "ppmu_left", "ppmu_right",
> > +	- "aclk_400", "aclk_266", "aclk_200", "aclk_160", "aclk_gdl", "aclk_gdr", "mfc";
> > + - clocks : phandles and specifiers for clocks listed in clock-names property
> > + - vdd_mif-supply : phandle to INT voltage regulator
> 
> s/_/-/ here too.

OK

Thanks for feedback.

Best regards,
Krzysztof


> Thanks,
> Mark.
> 
> > +
> > +Example
> > +=======
> > +	busfreq_mif: busfreq@106A0000 {
> > +		compatible = "samsung,exynos3250-busfreq-mif";
> > +		reg = <0x106A0000 0x2000>, <0x106B0000 0x2000>;
> > +		clocks = <&cmu_dmc CLK_DIV_DMC>;
> > +		clock-names = "dmc";
> > +		vdd_mif-supply = <&buck1_reg>;
> > +		status = "okay";
> > +	};
> > +
> > +	busfreq_int: busfreq@116A0000 {
> > +		compatible = "samsung,exynos3250-busfreq-int";
> > +		reg = <0x116A0000 0x2000>, <0x112A0000 0x2000>;
> > +		clocks = <&cmu CLK_PPMULEFT>,
> > +			<&cmu CLK_PPMURIGHT>,
> > +			<&cmu CLK_DIV_ACLK_400_MCUISP>,
> > +			<&cmu CLK_DIV_ACLK_266>,
> > +			<&cmu CLK_DIV_ACLK_200>,
> > +			<&cmu CLK_DIV_ACLK_160>,
> > +			<&cmu CLK_DIV_GDL>,
> > +			<&cmu CLK_DIV_GDR>,
> > +			<&cmu CLK_DIV_MFC>;
> > +		clock-names = "ppmuleft",
> > +			"ppmuright",
> > +			"aclk_400",
> > +			"aclk_266",
> > +			"aclk_200",
> > +			"aclk_160",
> > +			"aclk_gdl",
> > +			"aclk_gdr",
> > +			"mfc";
> > +		vdd_int-supply = <&buck3_reg>;
> > +		status = "okay";
> > +	};
> > -- 
> > 1.9.1
> > 
> > --
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