linux-kernel - Re: [PATCH v2 3/3] Documentation: mfd: Add binding document for S2MPA01

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Message-ID: <20140212181043.GB23630@e106331-lin.cambridge.arm.com>
Date:	Wed, 12 Feb 2014 18:10:43 +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>,
	"sbkim73@...sung.com" <sbkim73@...sung.com>,
	"lee.jones@...aro.org" <lee.jones@...aro.org>,
	"lgirdwood@...il.com" <lgirdwood@...il.com>,
	"broonie@...nel.org" <broonie@...nel.org>,
	"patches@...aro.org" <patches@...aro.org>
Subject: Re: [PATCH v2 3/3] Documentation: mfd: Add binding document for
 S2MPA01

Hi Sachin,

Apologies for the delay on this.

On Thu, Jan 09, 2014 at 11:22:34AM +0000, Sachin Kamat wrote:
> Added initial binding documentation for S2MPA01 MFD.
> 
> Signed-off-by: Sachin Kamat <sachin.kamat@...aro.org>
> ---
> * Re-organised as suggested by Mark Rutland.
> ---
>  Documentation/devicetree/bindings/mfd/s2mpa01.txt |   86 +++++++++++++++++++++
>  1 file changed, 86 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..70879b92b24b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/s2mpa01.txt
> @@ -0,0 +1,86 @@
> +
> +* 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.

Is the slave address not per-instance in I2C? If not why must is be 0x66?

> +
> +Optional properties:
> +- interrupt-parent: Specifies the phandle of the interrupt controller to which
> +  the interrupts from s2mpa01 are delivered to.
> +- interrupts: Interrupt specifier for interrupt source (connected to SoC).

The part in brackets can go. Assuming this is a single interrupt:

- interrupts: An interrupt-specifier for the sole interrupt generated by
  the device.

If the interrupt has a name it would be nice to mention that. If there
are more than one you should describe them.

> +
> +Optional nodes:
> +- regulators: The regulators of s2mpa01 that have to be instantiated should be
> +  included in a sub-node named 'regulators'. Regulator nodes and constraints
> +  included in this sub-node use the standard regulator bindings which are
> +  documented elsewhere.
> +
> +Properties for BUCK regulator nodes:
> + regulator-ramp-delay for BUCKs = [6250/12500(default)/25000/50000] uV/us

This could be made easier to read:

- regulator-ramp-delay: ramp delay in uV/us. May be 6250, 12500
  (default), 250000, or 50000. May be 0 for disabling the ramp delay on
  BUCK{1,2,3,4}.

> +
> + 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.

Can be folded into the above, as in my example.

> +
> +  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>.

Missing '=' before <value>?

> +  Grouping of BUCKs sharing ramp rate setting is as follow : BUCK[1, 6],
> +  BUCK[2, 4], and BUCK[8, 9, 10]

The following BUCKs share ramp settings:
* 1 and 6
* 2 and 4
* 8, 9, and 10

Thanks,
Mark.
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