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    SubjectRe: [PATCH v5 1/4] hwmon: ltc2978: device tree bindings documentation
    On Thu, Oct 02, 2014 at 01:37:48PM -0500, atull@opensource.altera.com wrote:
    > From: Alan Tull <atull@opensource.altera.com>
    >
    > Add device tree bindings documentation for ltc2978.
    >
    > Signed-off-by: Alan Tull <atull@opensource.altera.com>
    > ---
    > v2: clean whitespace
    > ---
    > .../devicetree/bindings/hwmon/ltc2978.txt | 41 ++++++++++++++++++++
    > 1 file changed, 41 insertions(+)
    > create mode 100644 Documentation/devicetree/bindings/hwmon/ltc2978.txt
    >
    > diff --git a/Documentation/devicetree/bindings/hwmon/ltc2978.txt b/Documentation/devicetree/bindings/hwmon/ltc2978.txt
    > new file mode 100644
    > index 0000000..b2d9c4d
    > --- /dev/null
    > +++ b/Documentation/devicetree/bindings/hwmon/ltc2978.txt
    > @@ -0,0 +1,41 @@
    > +ltc2978
    > +
    > +Required properties:
    > + - compatible: one of: ltc2974, ltc2977, ltc2978, ltc3880, ltc3883, ltm4676
    > + - reg: I2C address
    > +
    > +Optional properties:
    > + Name of the optional regulator subnode must be "regulators".

    This is currently a problem. The regulator core trats it as mandatory,
    meaning I get error messages such as

    ltc2978 5-005e: Failed to find regulator container node

    if not specified. We'll have to sort out with the regulator core how this should
    be handled.

    > + - #address-cells must be 1.
    > + - #size-cells must be 0.
    > +

    Checking this out, those do not seem to be necessary.

    > + For each regulator:
    > + - reg: regulator number

    This does not seem to be necessary either.

    > + - regulator-compatible: must be vout_en<regulator number> such as vout_en3
    > + valid range is:
    > + ltc2977, ltc2978 : vout_en0 - vout_en7
    > + ltc2974 : vout_en0 - vout_en3
    > + ltc3880, ltm4676 : vout_en0 - vout_en1
    > + ltc3883 : vout_en0 only

    Besides the unnecessary _en, this is a problem if there is more than one
    supported chip in the system, if DEBUG_FS is enabled, and if names are not
    specified in the devicetree file. I get a lot of error messages in a
    system with a large number of LTC2978 chips.

    vout3: Failed to create debugfs directory
    vout4: Failed to create debugfs directory
    vout5: Failed to create debugfs directory
    vout6: Failed to create debugfs directory
    vout7: Failed to create debugfs directory
    vout2: Failed to create debugfs directory
    vout3: Failed to create debugfs directory

    and so on (40+ times in my system). We will have to find a solution for this
    problem.

    I also get

    vout7: no parameters

    for each regulator which is a bit annoying with 50+ of those regulators
    in the system.

    Guenter

    > + - regulator-name: arbitrary name for regulator
    > +
    > +Example:
    > +ltc2978@5e {
    > + compatible = "ltc2978";
    > + reg = <0x5e>;
    > + regulators {
    > + #address-cells = <1>;
    > + #size-cells = <0>;
    > +
    > + vdacp0_reg: regulator@0 {
    > + reg = <0>;
    > + regulator-compatible = "vout_en0";
    > + regulator-name = "FPGA-2.5V";
    > + };
    > + vdacp2_reg: regulator@2 {
    > + reg = <2>;
    > + regulator-compatible = "vout_en2";
    > + regulator-name = "FPGA-1.5V";
    > + };
    > + };
    > +};
    > --
    > 1.7.9.5
    >


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