[PATCH v3 3/3] mtd: mtdpart: fix partitions searching

[Mikhail Kshevetskiy]

On 1/20/26 13:10, Quentin Schulz wrote:
> Hi Mikhail,
>
> On 1/19/26 11:33 PM, Mikhail Kshevetskiy wrote:
>> mtdpart internally enumerate partitions starting from zero, but
>> partition
>> driver API enumerate partitions starting from 1, so wrong partition will
>> be queried. This is wrong.
>>
>
> Are you sure this is the only place we need to fix that?
>
> Do mtd_parse_partitions, mtd_add_partition, mtd_del_partitions,
> add_mtd_partitions work as intended? They seem to also be using
> 0-starting indices... There's probably some mixing up between a device
> index (0-starting?) and a partition index (1-starting) I guess? 

Yes, I am pretty sure. 

The functions mtd_parse_partitions(), add_mtd_partitions()  and
mtd_free_parsed_partitions() are sused to parse mtd_parts string only
and not used in other places. They operates with temporary array,
removed by mtd_free_parsed_partitions() after the parsing was finished.
So no need to worry about them.

The functions mtd_add_partition() and mtd_del_partition() are linux only
defined. They are placed under

       #ifndef __UBOOT__
<https://elixir.bootlin.com/u-boot/v2026.01/C/ident/__UBOOT__>       #endif

condition, so does not compiles during U-Boot building.


>
> Would be nice if we could have some tests in test/ so that 1) we know
> it works as expected, 2) we avoid regressions in the future? 

Do you mean generic U_BOOT_PART_TYPE interface test or generic interface
test + special test for every available interface?

>
> Also in v2 you said not many devices do have both MTD_PARTITIONS and
> MTD_BLOCK enabled but I don't understand where MTD_BLOCK is required.
> Are we missing a symbol dependency somewhere? 
>
I think U_BOOT_PART_TYPE(mtd) interface should be conditionally compiled
if CONFIG_MTD_BLOCK is defined. As I can see this interface is needed
for commands like "part" and "read" , "write".

Without CONFIG_MTD_BLOCK we have

=> mtd list
List of MTD devices:
* spi-nand0
...
  - 0x000000000000-0x000010000000 : "spi-nand0"
      - 0x000000000000-0x000000100000 : "bl2"
      - 0x000000100000-0x000010000000 : "ubi"

so we have 2 MTD partitions: "bl2" and "ubi", but

=> part list mtd 0
=> read mtd 0#bl2 $loadaddr 0 2
** Bad device specification mtd 0#bl2 **
** Bad device specification mtd 0#bl2 **
Couldn't find partition mtd 0#bl2

means no MTD partition information can be used.

> Cheers,
> Quentin