On 18/04/18 12:41, Alban wrote:
On Tue, 17 Apr 2018 18:00:40 +0200
Alban <al...@free.fr> wrote:

On Tue, 17 Apr 2018 16:44:01 +0100
Srinivas Kandagatla <srinivas.kandaga...@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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