[cmd] clarification on syntax of 'chpart' command

[cmd] clarification on syntax of 'chpart' command

[Adarsh Babu Kalepalli]

Hi,

u-boot version: U-Boot 2021.07-rc1
Board: Beaglebone Black

I was trying to verify and use 'chpart' command on Beaglebone black with an
SDHC card ( with multiple partitions ) and am unable to get its exact
syntax.Is this command applicable to
any particular category of storage devices (viz. NOR flash,NAND flash etc)??
I tried using it as in its "help output" and also other combinations,
Am I missing anything,Please suggest its correct usage.

--------------------------------------------------------------------------------------------
Output Log from U-boot shell:
----------------------------------------
=> mmc list
OMAP SD/MMC: 0 (SD)
OMAP SD/MMC: 1
=> mmc dev 0
switch to partitions #0, OK
mmc0 is current device
=> mmc part

Partition Map for MMC device 0  --   Partition Type: DOS

Part    Start Sector    Num Sectors     UUID            Type
  1     2048            524288          11d09956-01     0c Boot
  2     526336          524288          11d09956-02     0c
  3     1050624         524288          11d09956-03     83
  4     1574912         524288          11d09956-04     83
=> chpart mmc0:2
Device nand0 not found!
=> chpart mmc0:3
Device nand0 not found!
=> chpart mmc2
Device nand0 not found!
=> chpart
Device nand0 not found!
=> help chpart
chpart - change active partition

Usage:
chpart part-id
    - change active partition (e.g. part-id = nand0,1)
=>
=> chpart part-id=mmc0
Device nand0 not found!
=> chpart part-id=mmc1
Device nand0 not found!
=> chpart part-id = mmc1
chpart - change active partition

Usage:
chpart part-id
    - change active partition (e.g. part-id = nand0,1)
=>
---------------------------------------------------------------------------------------------
Regards,
Adarsh

[cmd] clarification on syntax of 'chpart' command

[Wolfgang Denk]

Dear Adarsh,

In message <CAJgxa7eTn4L5Jbg2YbDExPFc1_69viALtW2YQYHj9VsU7xzQbA@mail.gmail.com> you wrote:
>
> I was trying to verify and use 'chpart' command on Beaglebone black with an
> SDHC card ( with multiple partitions ) and am unable to get its exact
> syntax.Is this command applicable to
> any particular category of storage devices (viz. NOR flash,NAND flash etc)??

I agree that it is not obvious from the help output, but the fact
that the chpart command is implemented in the cmd/mtdparts.c source
file gives a clear hint: it works only for MTD devices, not for
general storage devides using DOS (or GPT) partitions.

> => mmc dev 0
> switch to partitions #0, OK
> mmc0 is current device

This is what you should look for.  THe help output shoud tell you:

	...
	mmc dev [dev] [part] - show or set current mmc device [partition]
	...

So instead of

> => chpart mmc0:2
> Device nand0 not found!

you would use:

	=> mmc dev 0 2

Hope this helps.

Wolfgang Denk

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