Re: [PATCH v6 4/6] dt-bindings: cache: r9a07g043f-l2-cache: Add DT binding documentation for L2 cache controller

Geert Uytterhoeven
2023-01-09T12:16:01Z

Hi Prabhakar,

On Sat, Jan 7, 2023 at 9:47 PM Lad, Prabhakar
<prabhakar.csengg@gmail.com> wrote:
> On Fri, Jan 6, 2023 at 9:53 PM Conor Dooley <conor@kernel.org> wrote:
> > On Fri, Jan 06, 2023 at 06:55:24PM +0000, Prabhakar wrote:
> > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > >
> > > Add DT binding documentation for L2 cache controller found on RZ/Five SoC.
> > >
> > > The Renesas RZ/Five microprocessor includes a RISC-V CPU Core (AX45MP
> > > Single) from Andes. The AX45MP core has an L2 cache controller, this patch
> > > describes the L2 cache block.
> > >
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > > Reviewed-by: Rob Herring <robh@kernel.org>

> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/cache/andestech,ax45mp-cache.yaml
> > > @@ -0,0 +1,81 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +# Copyright (C) 2022 Renesas Electronics Corp.
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/cache/andestech,ax45mp-cache.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Andestech AX45MP L2 Cache Controller
> > > +
> > > +maintainers:
> > > + - Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > > +
> > > +description:
> > > + A level-2 cache (L2C) is used to improve the system performance by providing
> > > + a large amount of cache line entries and reasonable access delays. The L2C
> > > + is shared between cores, and a non-inclusive non-exclusive policy is used.
> > > +
> > > +select:
> > > + properties:
> > > + compatible:
> > > + contains:
> > > + enum:
> > > + - andestech,ax45mp-cache
> > > +
> > > + required:
> > > + - compatible
> > > +
> > > +properties:
> > > + compatible:
> > > + items:
> > > + - const: andestech,ax45mp-cache
> > > + - const: cache
> >
> > You might find value in a specific compatible for your SoC & enforce
> > constraints for it. Or you might not & I don't care either way :)
> >
> Good point actually. Geert what do you think?

That might be prudent, to cater for the way the standard AX45MP cache
block is integrated into the RZ/Five (or any other) SoC.

Still, in the absence of an SoC-specific compatible value, you can
handle integration issues using soc_device_match().

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds