Re: [PATCH v2 1/5] dt-bindings: sram: sunxi-sram: Add A523 compatible

[Andre Przywara <andre.przywara@arm.com>]

On Mon, 28 Apr 2025 12:21:56 +0000
Yixun Lan <dlan@gentoo.org> wrote:

> Hi Krzysztof,
> 
> On 09:21 Mon 28 Apr     , Krzysztof Kozlowski wrote:
> > On Thu, Apr 24, 2025 at 06:08:39PM GMT, Yixun Lan wrote:  
> > > The Allwinner A523 family of SoCs have their "system control" registers
> > > compatible to the A64 SoC, so add the new SoC specific compatible string.
> > > 
> > > Reviewed-by: Andre Przywara <andre.przywara@arm.com>
> > > Signed-off-by: Yixun Lan <dlan@gentoo.org>
> > > ---
> > >  .../devicetree/bindings/sram/allwinner,sun4i-a10-system-control.yaml     | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/sram/allwinner,sun4i-a10-system-control.yaml b/Documentation/devicetree/bindings/sram/allwinner,sun4i-a10-system-control.yaml
> > > index a7236f7db4ec34d44c4e2268f76281ef8ed83189..e7f7cf72719ea884d48fff69620467ff2834913b 100644
> > > --- a/Documentation/devicetree/bindings/sram/allwinner,sun4i-a10-system-control.yaml
> > > +++ b/Documentation/devicetree/bindings/sram/allwinner,sun4i-a10-system-control.yaml
> > > @@ -50,6 +50,7 @@ properties:
> > >            - enum:
> > >                - allwinner,sun50i-a100-system-control
> > >                - allwinner,sun50i-h6-system-control
> > > +              - allwinner,sun55i-a523-system-control
> > >            - const: allwinner,sun50i-a64-system-control  
> > 
> > No update for the children (sram)?
> >   
> No, I don't think there is sub node for sram
> From address map of A527, there is total 4KB size space of
> this section which unlikely has sram available.

That's something else, though. This system controller here *also* contains
a register to switch access to SRAM blocks between the CPU and the devices.
The actual SRAM blocks are somewhere else (hence the empty ranges;
property), check the H616 for instance:
	syscon: syscon@3000000 {
		compatible = "allwinner,sun50i-h616-system-control";
		reg = <0x03000000 0x1000>;
		#address-cells = <1>;
		#size-cells = <1>;
		ranges;

		sram_c: sram@28000 {
			compatible = "mmio-sram";
			reg = <0x00028000 0x30000>;

Krzysztof, we haven't worked out the SRAM regions yet, we typically add
them only when we need them. I think the display engine is a prominent
user, and support for that is quite a bit out at the moment.

From a compatibility standpoint it should be fine to leave this empty for
now, if I am not mistaken?

Cheers,
Andre

> but I do see some BROM/SRAM space from 0x0000 0000 - 0x0006 3FFF ..
> (which should not be relavant to this patch series..)
>