mtd concat OF question

[Grant Likely]

On Mon, Jan 24, 2011 at 03:37:49PM +0300, Stanislav O. Bezzubtsev wrote:
> Hello all.
> 
> 1) Is there an ability to specify in .dts an mtd_concat partition that
> consists of several parts of a same flash drive?
> For example, let there be 2MB flash drive and for some hardware limitations
> u-boot can be stored only at 1MB offset. So, can I specify an mtd device to
> own [0 -- 1MB] and [1.5MB -- 2MB]? As far as I can see (from
> the drivers/mtd/ofpart.c) there is no support for such a feature.

I don't think so, no.

> 2) If the answer on the previous question is "no". What shall be the most
> natural way to enhance the dts format? As for me it seems to be reasonable
> to allow partition regs description to consists more then of 2 values (N
> pairs). Example is below:
> 
> nor-flash at 0,0 {
>     compatible = "amd,s29gl01gp", "cfi-flash";
>     bank-width = <2>;
>     reg = <0x0 0x200000>;
>     #address-cells = <1>;
>     #size-cells = <1>;

BTW, you're missing a 'ranges' property here (It appears that the
documentation is missing it too, which definitely needs to be fixed).

>     partition at 100000 {
>         label = "uboot";
>         reg = <0x100000 0x80000>;
>         read-only;
>     };
> 
>     partition at 0 {
>         label = "user";
>         reg = <0x000000 0x100000
>                   0x180000 0x80000>;

Yes, I think this sounds reasonable, but the devil is in the
implementation.  Write a patch adding support for this binding, and
amend the documentation, and we'll see what it looks like.

g.