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

[Mathieu Poirier <mathieu.poirier@linaro.org>]

Good day Yann,

On Fri, Feb 02, 2024 at 10:14:08AM +0100, Arnaud POULIQUEN wrote:
> 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.
> 

I agree with Arnaud.  From a mechanical point of view it is interesting and
doesn't pause a serious technical challenge.  That said I don't really
understand the motivation behind the idea.  More details the exact problem you
want to fix would be welcomed.

> 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)?

Here too I have to agree with Arnaud.

> Regards,
> Arnaud
> 
> > 
> > Thanks!
> > 
> > Regards,
> >