Re: [PATCH v2 06/29] mtd: Add support for reading MTD devices via the nvmem API

Srinivas Kandagatla
2018-08-21T13:34:44Z

On 21/08/18 12:31, Boris Brezillon wrote:
>> * struct nvmem_config - NVMEM device configuration
>> @@ -58,6 +62,7 @@ struct nvmem_config {
>> bool root_only;
>> nvmem_reg_read_t reg_read;
>> nvmem_reg_write_t reg_write;
>> + nvmem_match_t match;
>> int size;
>> int word_size;
>> int stride;
>>
> That might work if nvmem cells are defined directly under the mtdnode.
Layout should not matter! which is the purpose of this callback.

The only purpose of this callback is to tell nvmem core that the
node(nvmem cell) belongs to that provider or not, if it is then we
successfully found the provider. Its up to the provider on which layout
it describes nvmem cells. Additionally the provider can add additional
sanity checks in this match function to ensure that cell is correctly
represented.

> If we go for this approach, I'd recommend replacing this ->match() hook
> by ->is_nvmem_cell() and pass it the cell node instead of the nvmem
> node, because what we're really after here is knowing which subnode is
> an nvmem cell and which subnode is not.

I agree on passing cell node instead of its parent. Regarding basic
validating if its nvmem cell or not, we can check compatible string in
nvmem core if we decide to use "nvmem-cell" compatible.

Also just in case if you missed this, nvmem would not iterate the

--srini