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

From: Srinivas Kandagatla
Date: Tue Aug 21 2018 - 09:35:07 EST

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