linux-kernel - Re: [PATCH 3/3] Documentation: mfd: Add binding document for S2MPA01

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Message-ID: <20140108094104.GC6701@e106331-lin.cambridge.arm.com>
Date:	Wed, 8 Jan 2014 09:41:04 +0000
From:	Mark Rutland <mark.rutland@....com>
To:	Sachin Kamat <sachin.kamat@...aro.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"broonie@...nel.org" <broonie@...nel.org>,
	"lee.jones@...aro.org" <lee.jones@...aro.org>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"lgirdwood@...il.com" <lgirdwood@...il.com>,
	"sameo@...ux.intel.com" <sameo@...ux.intel.com>,
	"sbkim73@...sung.com" <sbkim73@...sung.com>,
	"patches@...aro.org" <patches@...aro.org>
Subject: Re: [PATCH 3/3] Documentation: mfd: Add binding document for
 S2MPA01

On Wed, Jan 08, 2014 at 06:26:30AM +0000, Sachin Kamat wrote:
> Added initial binding documentation for S2MPA01 MFD.
> 
> Signed-off-by: Sachin Kamat <sachin.kamat@...aro.org>
> ---
>  Documentation/devicetree/bindings/mfd/s2mpa01.txt |   91 +++++++++++++++++++++
>  1 file changed, 91 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/s2mpa01.txt
> 
> diff --git a/Documentation/devicetree/bindings/mfd/s2mpa01.txt b/Documentation/devicetree/bindings/mfd/s2mpa01.txt
> new file mode 100644
> index 000000000000..ae750a28821b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/s2mpa01.txt
> @@ -0,0 +1,91 @@
> +
> +* Samsung S2MPA01 Voltage and Current Regulator
> +
> +The Samsung S2MPA01 is a multi-function device which includes high
> +efficiency buck converters including Dual-Phase buck converter, various LDOs,
> +and an RTC. It is interfaced to the host controller using an I2C interface.
> +Each sub-block is addressed by the host system using different I2C slave
> +addresses.
> +
> +Required properties:
> +- compatible: Should be "samsung,s2mpa01-pmic".
> +- reg: Specifies the I2C slave address of the PMIC block. It should be 0x66.
> +
> +Optional properties:
> +- interrupt-parent: Specifies the phandle of the interrupt controller to which
> +  the interrupts from s2mpa01 are delivered to.
> +- interrupts: Interrupt specifiers for interrupt sources.

That sounds a bit odd. How many interrupts might there be? What do they
signal?

> +
> +Optional nodes:
> +- regulators: The regulators of s2mpa01 that have to be instantiated should be
> +included in a sub-node named 'regulators'. Regulator nodes included in this
> +sub-node should be of the format as listed below.
> +
> +	regulator_name {
> +		[standard regulator constraints....];
> +	};
> +

Why not just say that the regulators node contains regulators in the
usual format, with reference to the regulator binding?

> + regulator-ramp-delay for BUCKs = [6250/12500(default)/25000/50000] uV/us
> +
> + BUCK[1/2/3/4] supports disabling ramp delay on hardware, so explictly
> + regulator-ramp-delay = <0> can be used for them to disable ramp delay.
> + In the absence of the regulator-ramp-delay property, the default ramp
> + delay will be used.
> +
> +NOTE: Some BUCKs share the ramp rate setting i.e. same ramp value will be set
> +for a particular group of BUCKs. So provide same regulator-ramp-delay<value>.
> +Grouping of BUCKs sharing ramp rate setting is as follow : BUCK[1, 6],
> +BUCK[2, 4], and BUCK[8, 9, 10]

It would probably be better to have a heading like "Properties for BUCK
regulator nodes" for all of the above.


> +
> +The regulator constraints inside the regulator nodes use the standard regulator
> +bindings which are documented elsewhere.

As mentioned above, state this at the beginning and point to the
regulator bindings.

> +
> +The following are the names of the regulators that the s2mpa01 PMIC block
> +supports. Note: The 'n' in LDOn and BUCKn represents the LDO or BUCK number
> +as per the datasheet of s2mpa01.

So these are what the nodes should be called? (rather than values for
regulator-name).

Otherwise this looks ok to me.

Thanks,
Mark.
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