Re: [PATCH v5 6/6] soc: renesas: Add L2 cache management for RZ/Five SoC

Conor Dooley
2022-12-19T18:07:46Z

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On Mon, Dec 19, 2022 at 12:43:44PM +0000, Lad, Prabhakar wrote:
> Hi Conor,
>
> On Sat, Dec 17, 2022 at 10:52 PM Conor Dooley <conor@kernel.org> wrote:
> >
> > On Fri, Dec 16, 2022 at 09:04:20PM +0100, Arnd Bergmann wrote:
> > > On Fri, Dec 16, 2022, at 17:32, Palmer Dabbelt wrote:
> > > > On Thu, 15 Dec 2022 23:02:58 PST (-0800), Christoph Hellwig wrote:
> > > >> On Thu, Dec 15, 2022 at 01:40:30PM -0800, Palmer Dabbelt wrote:
> > > >>> Given that we already moved the SiFive one out it seems sane to just start
> > > >>> with the rest in drivers/soc/$VENDOR. Looks like it was Christoph's idea to
> > > >>> do the move, so I'm adding him in case he's got an opinion (and also the SOC
> > > >>> alias, as that seems generally relevant).
> > > >>
> > > >> Well, it isn't an integral architecture feature, so it doesn't really
> > > >> beloing into arch. Even the irqchip and timer drivers that are more
> > > >> less architectural are in drivers/ as they aren't really core
> > > >> architecture code.
> > > >
> > > > That makes sense to me, it just looks like the SiFive ccache is the only
> > > > one that's in drivers/soc/$VENDOR, the rest are in arch. It looks like
> > > > mostly older ports that have vendor-specific cache files in arch (ie,
> > > > arm has it but arm64 doesn't). Maybe that's just because the newer
> > > > architectures sorted out standard ISA interfaces for these and thus
> > > > don't need the vendor-specific bits? I think we're likely to end up
> > > > with quite a few of these vendor-specific cache management schemes on
> > > > RISC-V.
> > > >
> > > > I'm always happy to keep stuff out of arch/riscv, though. So maybe we
> > > > just buck the trend here and stick to drivers/soc/$VENDOR like we did
> > > > for the first one?
> > >
> > > I don't particularly like drivers/soc/ to become more of a dumping
> > > ground for random drivers. If there are several SoCs that have the
> > > same requirement to do a particular thing, the logical step would
> > > be to put them into a proper subsystem, with a well-defined interface
> > > to dma-mapping and virtualization frameworks.
> > >
> > > The other things we have in drivers/soc/ are usually either
> > > soc_device drivers for identifying the system, or they export
> > > interfaces used by soc specific drivers.
> >
> > Sounds like that's two "not in my back yard" votes from the maintainers
> > in question..
> > Doing drivers/cache would allow us to co-locate the RISC-V cache
> > management bits since it is not just going to be the ax45mp l2 driver
> > that will need to have them.
> >
> > Would it be okay to put this driver in soc/andestech for now & then move
> > it, and the SiFive one, once we've got patches posted for cache
> > management with that?
> >
> I think to start with it would be better if we place the Andes cache
> driver in the proposed "drivers/cache" folder. We would avoid
> unnecessary movement of code?

Uh, go for it I guess. I'll try to put out a few patches for moving the
sifive ccache driver & adding management stuff to it whenever I
inevitably get bored over Christmas.
The offer to make me responsible for applying patches for drivers/cache
still stands.

Thanks,
Conor.

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