[PATCH v3 1/3] nvmem: Update the OF binding to use a subnode for the cells list

[Srinivas Kandagatla]

On 18/04/18 14:34, Alban wrote:
> On Wed, 18 Apr 2018 13:53:56 +0100
> Srinivas Kandagatla <srinivas.kandagatla at linaro.org> wrote:
> 
>> On 18/04/18 13:32, Alban wrote:
>>>> 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 at 0 {
>>>> 	#address-cells = <1>;
>>>> 	#size-cells = <1>;
>>>> 	compatible = "s25sl064a";
>>>> 	reg = <0>;
>>>>
>>>> 	nvmem-cells {
>>>> 		compatible = "mtd-nvmem";
>>>> 		#address-cells = <1>;
>>>> 		#size-cells = <1>;
>>>>
>>>> 		calibration: calib at 404 {
>>>> 			reg = <0x404 0x10>;
>>>> 		};
>>>> 	};
>>>> };
>>> But the root cause is in the nvmem binding, this conflict could exists
>> No, the root cause is because of passing wrong device instance to nvmem
>> core. And trying to workaround is the actual issue.
> 
> The data is stored on the MTD, so the nvmem provider is the MTD device.
> I don't think it is a good idea to have a virtual device in the DT to
> accommodate the nvmem API.
> 
Yep, I agree! this is same issue if we make nvmem-cells a child of nvmem 
provider too.

However, I would like to see this moving forward.

I can think of one possible solution here, which is, adding 
"nvmem-mtd-cell" or "nvmem-cell" compatible string to each cell. The 
problem you mentioned regarding #address-cells and #size-cells with 
provider need to be addressed in nvmem core.

Currently nvmem core only support offsets of 32 bits, if you are 
expecting a 64 bit offsets then we should add that as a feature to nvmem 
core.

nvmem core as it is today should work fine with 32 bit offsets for mtd 
cases.

what do you think?

thanks,
srini