linux-kernel - Re: [PATCH v2 1/3] dt-bindings: nvmem: add description for UniPhier eFuse

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Date:   Fri, 13 Oct 2017 13:42:18 -0500
From:   Rob Herring <robh@...nel.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Keiji Hayashibara <hayashibara.keiji@...ionext.com>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Masami Hiramatsu <masami.hiramatsu@...aro.org>,
        Jassi Brar <jaswinder.singh@...aro.org>,
        Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
        Kiyoshi Owada <owada.kiyoshi@...ionext.com>
Subject: Re: [PATCH v2 1/3] dt-bindings: nvmem: add description for UniPhier eFuse

On Fri, Oct 13, 2017 at 11:04 AM, Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
> Hi Rob,
>
>
> 2017-10-13 22:49 GMT+09:00 Rob Herring <robh@...nel.org>:
>> On Fri, Oct 06, 2017 at 02:02:58PM +0900, Keiji Hayashibara wrote:
>>> Add uniphier-efuse dt-bindings documentation.
>>>
>>> Signed-off-by: Keiji Hayashibara <hayashibara.keiji@...ionext.com>
>>> ---
>>>  .../devicetree/bindings/nvmem/uniphier-efuse.txt   | 49 ++++++++++++++++++++++
>>>  1 file changed, 49 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/nvmem/uniphier-efuse.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/nvmem/uniphier-efuse.txt b/Documentation/devicetree/bindings/nvmem/uniphier-efuse.txt
>>> new file mode 100644
>>> index 0000000..1a394e5
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/nvmem/uniphier-efuse.txt
>>> @@ -0,0 +1,49 @@
>>> += UniPhier eFuse device tree bindings =
>>> +
>>> +This UniPhier eFuse must be under soc-glue.
>>> +
>>> +Required properties:
>>> +- compatible: should be "socionext,uniphier-efuse"
>>> +- reg: should contain the register location and length
>>> +
>>> += Data cells =
>>> +Are child nodes of efuse, bindings of which as described in
>>> +bindings/nvmem/nvmem.txt
>>> +
>>> +Example:
>>> +
>>> +     soc-glue@...00000 {
>>> +             compatible = "socionext,uniphier-ld20-soc-glue-debug",
>>> +                          "simple-mfd";
>>> +             #address-cells = <1>;
>>> +             #size-cells = <1>;
>>> +             ranges = <0x0 0x5f900000 0x2000>;
>>> +
>>> +             efuse@100 {
>>> +                     compatible = "socionext,uniphier-efuse";
>>> +                     reg = <0x100 0x28>;
>>> +             };
>>> +
>>> +             efuse@200 {
>>> +                     compatible = "socionext,uniphier-efuse";
>>> +                     reg = <0x200 0x68>;
>>> +                     #address-cells = <1>;
>>> +                     #size-cells = <1>;
>>> +
>>> +                     /* Data cells */
>>> +                     usb_mon: usb_mon {
>>
>> Don't use '_' and needs a unit-address. Build your dtb with W=2 option
>> and you'll get these warnings.
>
>
> Do you mean "usb_mon: usb-mon@54" ?

Yes.

> DT files in kernel sprinkle tons of warnings even with W=1.
>
> I always eliminate W=1, so I agree with "@54".
>
> I do not care W=2 much.
> If you see arch/arm64/boot/dts/socionext/uniphier-ld20.dtsi,
> yeah, I generally use '-' for node names, but I see some exceptions.
>
> You admitted -Wnode_name_chars_strict is "subjective"
> in commit 8654cb8d0371.

Yes, meaning fixing existing cases is questionable and I'd put doing
so at a lower priority. I didn't mean it is up to each person to
decide whether they like to use '_' or not.

> If you are unhappy about it, we can fix,
> but I am not sure how picky we should be.

Let me put it clearly: Don't add new warnings with W=2.


>
>
>>> +                             reg = <0x54 0xc>;
>>
>> Without ranges above, this is address 5f900054. I think you want
>> 5f900254. You need:
>>
>> ranges = <0x0 0x200 0x68>;
>
>
> I do not get it.
>
> The parent is an efuse, not any kind of bus.
>
> <0x54, 0c> just represents the offset and size
> within the efuse device, so this is not mapped in
> CPU address view.
> The is apparent from of_nvmem_cell_get().
>
> Some efuse devices _may_ be directly accessed
> as MMIO from CPU, but it is abstracted under an efuse driver.
>
> I believe missing "ranges" is correct.

Okay, you're right. If those are not memory mapped then it is fine.

Rob