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SubjectRe: [PATCH v3 1/3] nvmem: Update the OF binding to use a subnode for the cells list
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On 18/04/18 12:41, Alban wrote:
> On Tue, 17 Apr 2018 18:00:40 +0200
> Alban <albeu@free.fr> wrote:
>
>> On Tue, 17 Apr 2018 16:44:01 +0100
>> Srinivas Kandagatla <srinivas.kandagatla@linaro.org> wrote:
>>
>>> Thanks for explaining,
>>>
>>> On 17/04/18 15:54, Alban wrote:
>>>> This will not only allow reading the calibration data from nvmem, but
>>>> will also create a partition on the MTD device, which is not acceptable.
>>>> With my proposed binding this would become:
>>>>
>>>> flash@0 {
>>>> #address-cells = <1>;
>>>> #size-cells = <1>;
>>>> compatible = "s25sl064a";
>>>> reg = <0>;
>>>>
>>>> nvmem-cells {
>>>> compatible = "nvmem-cells";
>>>> #address-cells = <1>;
>>>> #address-cells = <1>;
>>>>
>>>> calibration: calib@404 {
>>>> reg = <0x404 0x10>;
>>>> };
>>>> };
>>>
>>> Why can't we make nvmem-cells node a nvmem provider in this case?
>>> Which should work!
>>
>> TBH I just copied what have been done to fix the same problem with the
>> MTD partitions. But yes we could also just extend the current binding
>> to require a compatible string on each nvmem-cell, which would not
>> require any code change to support.
>
> However this scheme will not work if the device node binding already
> have subnodes with addresses. The addressing, as specified by
> #address-cells and #size-cells, might be incompatible or might overlap.
> Using the nvmem-cells subnode solve this problem.
>

I was also suggesting you to use nvmem-cell subnode, but make it a
proper nvmem provider device, rather than reusing its parent device.

You would end up some thing like this in dt.

flash@0 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "s25sl064a";
reg = <0>;

nvmem-cells {
compatible = "mtd-nvmem";
#address-cells = <1>;
#size-cells = <1>;

calibration: calib@404 {
reg = <0x404 0x10>;
};
};
};

--srini

> Alban
>

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