On Fri, Sep 30, 2016 at 11:38:29AM +0000, Bhaskar U wrote:

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-----Original Message-----
From: Scott Wood
Sent: Tuesday, September 06, 2016 10:36 PM
To: Shawn Guo <shawnguo@kernel.org>; Stuart Yoder <redacted>;
Rob Herring [off-list ref]; Mark Rutland [off-list ref]
Cc: devicetree at vger.kernel.org; Bhaskar U <redacted>; Scott
Wood [off-list ref]; Prabhakar Kushwaha
[off-list ref]; linux-devel at gforge.freescale.net; Pratiyush
Srivastava [off-list ref]; linux-arm-
kernel at lists.infradead.org
Subject: Re: [linux-devel] [PATCH v2 1/1] arm64: Add DTS support for FSL's
LS1012A SoC

On 09/04/2016 08:47 PM, Shawn Guo wrote:

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On Tue, Aug 30, 2016 at 02:07:17PM +0000, Stuart Yoder wrote:

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On Mon, Aug 29, 2016 at 12:51:01PM -0500, Scott Wood wrote:

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On Mon, 2016-08-29 at 17:52 +0800, Shawn Guo wrote:

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On Fri, Aug 26, 2016 at 03:57:21PM +0530, Bhaskar Upadhaya wrote:

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+		clockgen: clocking at 1ee1000 {
+			compatible = "fsl,ls1012a-clockgen";

The compatible cannot be found in binding docs.

From Documentation/devicetree/bindings/clock/qoriq-clock.txt:

- compatible: Should contain a chip-specific clock block compatible
        string and (if applicable) may contain a chassis-version clock
        compatible string.

        Chip-specific strings are of the form "fsl,<chip>-clockgen", such as:
        * "fsl,p2041-clockgen"
        * "fsl,p3041-clockgen"
        * "fsl,p4080-clockgen"
        * "fsl,p5020-clockgen"
        * "fsl,p5040-clockgen"
        * "fsl,t4240-clockgen"
        * "fsl,b4420-clockgen"
        * "fsl,b4860-clockgen"
        * "fsl,ls1021a-clockgen"
        Chassis-version clock strings include:
        * "fsl,qoriq-clockgen-1.0": for chassis 1.0 clocks
        * "fsl,qoriq-clockgen-2.0": for chassis 2.0 clocks

I really hope we don't have to update every single
fsl,<chip>-whatever binding every time a new chip comes out.  There
are already other chips not listed, FWIW (e.g. t1040, t2080, ls1043a, and

ls2080a).  That's why it says "such as".

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If I remember correctly, DT maintainers want every supported
compatible string explicitly listed in bindings doc.  And they even
added a check into checkpatch.pl with commit bff5da433525
("checkpatch: add DT compatible string documentation checks").

See Documentation/devicetree/bindings/submitting-patches.txt:

  5) The wildcard "<chip>" may be used in compatible strings, as in
     the following example:

         - compatible: Must contain '"nvidia,<chip>-pcie",
           "nvidia,tegra20-pcie"' where <chip> is tegra30, tegra132, ...

     As in the above example, the known values of "<chip>" should be
     documented if it is used.

It _is_ allowed to use the <chip> wildcard, and so you will not find
all full compatible strings explicitly listed in bindings.  However,
the chips themselves "should" be listed.

+ Rob and Mark

Oops, I'm not aware of this DT document.  In that case, the DT
document and checkpatch is basically asking for conflicting thing.
Rob, Mark, can you guys please clarify?

Checkpatch is a useful tool but it can't get everything right all the time.

So what should we do, shall I add "compatible = "fsl,ls1012a-clockgen";" in Documentation/devicetree/bindings/clock/qoriq-clock.txt ?

I would encourage you to do that.

Shawn