Message-ID: <5150906F.9040202@wwwdotorg.org>
Date:	Mon, 25 Mar 2013 11:59:11 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Ian Lartey <ian@...mlogic.co.uk>
CC:	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
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Subject: Re: [PATCH v10 01/12] mfd: DT bindings for the palmas family MFD

On 03/22/2013 08:55 AM, Ian Lartey wrote:
> From: Graeme Gregory <gg@...mlogic.co.uk>
> 
> Add the various binding files for the palmas family of chips. There is a
> top level MFD binding then a seperate binding for IP blocks on chips.

> diff --git a/Documentation/devicetree/bindings/clock/palmas-clk.txt b/Documentation/devicetree/bindings/clock/palmas-clk.txt

Where is the reg property; if you're instantiating the clk device as a
standalone DT node and driver, it should be possible to retrieve the
address of this IP block instance from DT, not using driver-internal APIs.

This same comment likely applies everywhere, so I won't repeat it.

> +Example:
> +
> +clk {
> +    compatible = "ti,twl6035-clk", "ti,palmas-clk";
> +    ti,clk32kg-mode-sleep = <0>;
> +    ti,clk32kgaudio-mode-sleep = <0>;

> +    #clock-cells = <1>;
> +    clock-frequency = <32000000>;
> +    clock-names = "clk32kg", "clk32kgaudio";

The binding description itself should describe what clocks this node
provides and consumes.

What is clock-frequency; which clock does it affect?

The presence of #clock-cells implies this is a clock provider. This
binding should define the format of the clock cells that this property
implies. I assume it's just the ID of the output clocks, but what values
correspond to which output clocks? That mapping table needs to be listed
here.

The presence of clock-names implies this is a clock consumer. However,
there is no clocks property in the example. Is clks missing from the
example, or should this property be clock-output-names instead? If this
node is a clock consumer, the list of which clocks it requires should be
documented.

> diff --git a/Documentation/devicetree/bindings/gpio/gpio-palmas.txt b/Documentation/devicetree/bindings/gpio/gpio-palmas.txt

> +- gpio-controller: mark the device as a GPIO controller
> +- gpio-cells = <1>:  GPIO lines are provided.

That's #gpio-cells not gpio-cells.

I assume that cell simply contains the GPIO ID/number. That should be
documented for clarity.

Surely gpio-cells should be 2 not 1, so there is space for flags. At
least an "inverted" or "active-low" flag should be included; GPIO
consumers would typically implement that flag in SW, so there' no
requirement that the flag only be supported if the HW supports the feature.

> +- interrupt-controller : palmas has its own internal IRQs
> +- #interrupt-cells : should be set to 2 for IRQ number and flags
> +  The first cell is the IRQ number.
> +  The second cell is the flags, encoded as the trigger masks from
> +  Documentation/devicetree/bindings/interrupts.txt

You need "/interrupt-controller" before the filename there.

> +- interrupt-parent : The parent interrupt controller.

If this IP block has interrupt outputs, it should require an
"interrupts" property too. This is the same concept that drives the need
for a reg property. This same comment likely applies everywhere, so I
won't repeat it.

> diff --git a/Documentation/devicetree/bindings/input/palmas-pwrbutton.txt b/Documentation/devicetree/bindings/input/palmas-pwrbutton.txt

> +- interrupts: the interrupt outputs of the controller.

How many entries are there, what do they mean, and in what order must
they appear? (Note that the binding of a node must define the order of
the interrupts property, since historically it's been accessed by index,
not by name, and all bindings must allow that access method to be used).

> +- interrupt-names : Should be the name of irq resource. Each interrupt
> +  binds its interrupt-name.

The binding needs to define standard names for the entries in this
property, or define that interrupts are only retrieved by index, in
which case interrupt-names shouldn't be present. This same comment
likely applies everywhere, so I won't repeat it.

> diff --git a/Documentation/devicetree/bindings/mfd/palmas.txt b/Documentation/devicetree/bindings/mfd/palmas.txt

> +Required properties:
...

I believe the Palmas devices have many separate I2C addresses, even
buses, which are I think are at least partially independently SW
configurable. In that case, the reg property for this node should
probably enumerate all the I2C addresses that this chip responds to, so
that they can each be passed down to the child nodes.

> diff --git a/Documentation/devicetree/bindings/regulator/palmas-pmic.txt b/Documentation/devicetree/bindings/regulator/palmas-pmic.txt

> +Optional nodes:
> +- regulators : should contain the constrains and init information for the
> +	       regulators. It should contain a subnode per regulator from the
> +	       list.
> +	       For ti,palmas-pmic - smps12, smps123, smps3 depending on OTP,
> +	       smps45, smps457, smps7 depending on varient, smps6, smps[8-10],
> +	       ldo[1-9], ldoln, ldousb
> +	       For ti,palmas-charger-pmic - smps12, smps123, smps3 depending on OTP,
> +	       smps[6-9], boost, ldo[1-14], ldoln, ldousb

The list of legal compatible values for this node above doesn't include
both ti,palmas-pmic and ti,palmas-charger-pmic. Should it? This node
should describe this PMIC block in a completely standalone fashion,
without the need to go look at the top-level node to see if it's a
"charger" variant or not.

> +	       optional chip specific regulator fields :-
> +	       ti,warm-reset - maintain voltage during warm reset
> +	       ti,roof-floor - control voltage selection by pin

I assume those are Boolean not integer. It's worth mentioning the type
of each property.
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