Re: [RFC] Passing device-tree to remoteproc?

[Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>]

Hello Yann,

On 1/30/24 11:20, Yann Sionneau wrote:
> Hello,
> 
> On 1/23/24 14:32, Yann Sionneau wrote:
>> Hello,
>>
>> How interesting to upstream Linux would it be to have a way for Linux kernel
>> or user space to pass a device tree blob to remote processor when starting a
>> remote proc FW?
>>
>> For instance we could imagine something like this:
>>
>> 1/ user space does echo -n firmware.elf >
>> /sys/class/remoteproc/remoteprocXXX/firmware
>>
>> 2/ user space does echo -n my_dt.dtb > /sys/class/remoteproc/remoteprocXXX/dtb
>>
>> 3/ user space does echo start > /sys/class/remoteproc/remoteprocXXX/state
> 
> Any opinion on this proposal?


Interesting use case. There is no concrete need in ST, but it raises the
question of providing extra data with the firmware to the remote processor.

In a first approach, my personal feeling is that the ELF and the DTB are
interdependent.
So having a mechanism to ensure coherency between both could be important.

Then it could be interesting to address the need in a more generic way
to be able to transfer extra data, for instance an audio tuning for a DSP.
Adding a specific sysfs for each specific need could not be a good idea in long
term.

Have you looked into some other approaches such as adding the DTB as a specific
section of your ELF file,or adding the support of a new format that packages
everything together (for instance FIP)?

Regards,
Arnaud

> 
> Thanks!
> 
> Regards,
>