Re: [PATCH 2/3] arm64: dts: r8a7796: Add CA53 L2 cache-controller node

On Fri, Feb 17, 2017 at 8:07 PM, Geert Uytterhoeven
[off-list ref] wrote:

On Fri, Feb 17, 2017 at 6:51 PM, Sudeep Holla [off-list ref] wrote:

quoted

On 17/02/17 15:30, Geert Uytterhoeven wrote:

quoted

Add a device node for the Cortex-A53 L2 cache-controller.

The L2 cache for the Cortex-A53 CPU cores is 512 KiB large (organized as
32 KiB x 16 ways).

Extracted from a patch by Takeshi Kihara in the BSP.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 arch/arm64/boot/dts/renesas/r8a7796.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/boot/dts/renesas/r8a7796.dtsi b/arch/arm64/boot/dts/renesas/r8a7796.dtsi
index 6c0a65abf9fd09eb..d848e94d7282e5aa 100644
--- a/arch/arm64/boot/dts/renesas/r8a7796.dtsi
+++ b/arch/arm64/boot/dts/renesas/r8a7796.dtsi

@@ -62,6 +62,14 @@
                      cache-unified;
                      cache-level = <2>;
              };
+
+             L2_CA53: cache-controller@100 {
+                     compatible = "cache";
+                     reg = <0x100>;

Is this not integrated L2 cache ? IIUC reg is MPIDR of the cpu and
representing it as cache controller with some reg value doesn't sound
correct IMO.

So this should be cache-controller-1, without a reg property?

BTW, that means the advice from https://lkml.org/lkml/2016/3/8/80:

| Just add a reg property. The values should probably match the MPIDR in
| some way (e.g. 0 and 100).

was wrong, and we should fix all cache-controller nodes that got "fixed"?

Having better DT documentation for caches on ARM would be nice...
There's only a (too) minimalist example in
Documentation/devicetree/bindings/arm/cpu-capacity.txt

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