Re: [PATCH v2 5/5] doc: board: document support for USB DFU boot on AM62Px SoC

[Roger Quadros <rogerq@kernel.org>]

On 19/12/2024 08:43, Siddharth Vadapalli wrote:
> On Wed, Dec 18, 2024 at 04:08:01PM +0200, Roger Quadros wrote:
> 
> Hello Roger,
> 
>>
>>
>> On 18/12/2024 14:45, Siddharth Vadapalli wrote:
> 
> [...]
> 
>>> +DFU based boot
>>> +--------------
>>> +
>>> +To boot the board over DFU, set the switches to DFU mode and connect to the
>>> +USB type C DRD port on the board. After power-on the build artifacts needs to be
>>> +uploaded one by one with a tool like dfu-util.
>>> +
>>> +The initial ROM will have a DFU alt named `bootloader` for the initial R5 spl
>>> +upload. The next stages as exposed by U-Boot have target alts matching the name
>>> +of the artifacts, for these a USB reset has to be done after each upload.
>>> +
>>> +When using dfu-util the following commands can be used to boot to a U-Boot shell:
>>> +
>>> +.. prompt:: bash $
>>> +
>>> +  dfu-util -a bootloader -D tiboot3.bin
>>> +  dfu-util -R -a tispl -D tispl.bin
>>> +  dfu-util -R -a u-boot.img -D u-boot.img
>>
>> Is there a known reason why -R was not used for the first command but required in last two?
>> What about if -R is not used for all 3 commands?
> 
> According to the "dfu-util" help menu, the "-R" option is defined as:
> "Issue USB Reset signalling once we're finished"
> 
> While the "-R" option is not required in the first stage / command, it
> is required in the next stages. Without "-R", the user would have to
> press "Ctrl+C" to proceed i.e. tispl.bin / u-boot.img are transferred
> / downloaded onto the device but not executed until user presses "Ctrl+C".
> 
> As to why "-R" is not required in the first stage, I suppose that ROM
> automatically executes tiboot3.bin after it has been transferred.
> 

Thanks Siddharth for the clarification.

-- 
cheers,
-roger