Re: [PATCH v3 1/2] remoteproc: elf_loader: Create new callback for copying segments to remote cpu

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

On Thu, Nov 05, 2026 at 02:41:37PM +0100, Uwe Kleine-König wrote:
> Hello,
> 
> On Thu, Nov 05, 2026 at 12:10:05PM +0000, sashiko-bot@kernel.org wrote:
> > > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> > > index 00019b1895e6e..e750a127cbc4a 100644
> > > --- a/include/linux/remoteproc.h
> > > +++ b/include/linux/remoteproc.h
> > > @@ -75,6 +75,7 @@ enum rsc_handling_status {
> > >   * @detach:	detach from a device, leaving it powered up
> > >   * @kick:	kick a virtqueue (virtqueue id given as a parameter)
> > >   * @da_to_va:	optional platform hook to perform address translations
> > > + * @memcpy_tova:optional platform hook to copy data into remote memory range
> > >   * @parse_fw:	parse firmware to extract information (e.g. resource table)
> > >   * @handle_rsc:	optional platform hook to handle vendor resources. Should return
> > >   *		RSC_HANDLED if resource was handled, RSC_IGNORED if not handled
> > > @@ -99,6 +100,9 @@ struct rproc_ops {
> > >  	int (*detach)(struct rproc *rproc);
> > >  	void (*kick)(struct rproc *rproc, int vqid);
> > >  	void * (*da_to_va)(struct rproc *rproc, u64 da, size_t len, bool *is_iomem);
> > > +	int (*memcpy_tova)(struct rproc *rproc, u64 da, const void *src,
> > > +			   size_t filesz, size_t memsz);
> > 
> > [Severity: Low]
> > This isn't a bug, but is memcpy_tova the best name for this callback in
> > struct rproc_ops?
> > 
> > Across the remoteproc subsystem (such as in struct rproc_mem_entry and
> > ops->da_to_va), da denotes a remote processor device address while va denotes
> > a kernel virtual address. Since rproc_elf_load_segments() passes the
> > untranslated device address da directly to this callback (including for
> > devices where remote memory is not mapped into CPU virtual address space at
> > all), calling it memcpy_tova seems somewhat misleading.
> > 
> > In addition, when rproc->ops->memcpy_tova is provided,
> > rproc_elf_load_segments() skips both the filesz copy and the trailing
> > memsz - filesz zeroing step. Should the kernel-doc comment for @memcpy_tova in
> > include/linux/remoteproc.h document that implementations must copy filesz
> > bytes to da and zero-fill the remaining memsz - filesz bytes when
> > memsz > filesz?
> 
> That's a valid concern. Maybe `populate_segment` would be a better name?
> I considered being more verbose in the kdoc entry, but all the other
> entries are very sparse, too, so didn't want to add a 5 line comment for
> the new callback among all the one-liners. But I can if you tell me your
> preferences.
>

I would stick with ->memcpy_tova() to keey the mcmcpy() semantic already
rproc_elf_load_segments().  But yes, go ahead and add the 5 line comment.

 
> Best regards
> Uwe