Re: [PATCH v2 1/3] nvmem: core: introduce cells parser

[Srinivas Kandagatla]

On 28/09/2021 14:31, Vadym Kochan wrote:
> > > > Can I note here that I would like to parse
> > > > TLV data from an SPI-NOR device to NVMEM cells.
> > > > The same general use case (getting mac-address from OEM data).
> > > >
> > > > Was planning to base my work on this series, as well as
> > > > https://lore.kernel.org/all/20210908100257.17833-1-qiangqing.zhang@xxxxxxx/
> > > > (thanks for pointing that out Srinivas)
> > > >
> > > > Cheers,
> > > What about at least to have just one call in core.c to make it a bit
> > > de-coupled, like:
> > Why do you want to decouple this? the provider driver should be very
> > well aware of the format the data layout.
> In my understanding nvmem device should not aware about the data layout
> (in case it does not rely on device's specific characteristics). Same
> cells layout (TLV, etc) might exist on other nvmem devices.
How would provider driver parse this without even knowing data layout?


> > Its fine to an extent to adding parse_cells() callback in nvmem_config.
> OK, in that case it will require small change in the core.
>
> > > core.c
> > >
> > > struct nvmem_device *nvmem_register(const struct nvmem_config *config)
> > > {
> > > ...
> > >            rval = nvmem_add_cells_from_table(nvmem);
> > >            if (rval)
> > >                    goto err_remove_cells;
> > >
> > > +        rval = nvmem_parse_cells(nvmem, of);
> > > +        if (rval) {
> > > +        /* err handling */
> > > +        }
> > > +
> > >            rval = nvmem_add_cells_from_of(nvmem);
> > >            if (rval)
> > >                    goto err_remove_cells;
> > >
> > >            blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
> > >
> > >            return nvmem;
> > >
> > > ...
> > >
> > > }
> > >
> > > somewhere in nvmem-parser.c:
> > However this is totally over kill.
> >
> > > /* retreive parser name from of_node and call appropriate function to parse
> > >      non-fixed cells and update via of_update */
> > This is completely provider drivers job, nothing nvmem core should worry
> > about.
> >
> > If you have concern of having code duplicated then we could make some of
> > the common functions as library functions, But it still is within the
> > scope of provider drivers.
> Do I understand correctly that this parser function should be exported
> from at24.c (in case of ONIE) and not from a separate C module ? Or
> it just means that if there will be more users of this parsing function
> then it might be moved to separate C module ?
yes.
For now am not really sure how many users are for such parsing function.

> > --srini
> BTW, what if such change will be declined by particular nvmem driver
> maintainer ?

You would need some changes to provider driver to be able to flag that 
there is some kind of parsing required anyway.

--srini
>