[PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver

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I'd suggest requiring #address-cells=<1> and #size-cells=<0> in the
master
node, and listing the children by reg property. If the address is not
easily expressed as a single integer, use a larger #address-cells
value.

We already have something equivalent to reg in "module-id" (see patch
02/11), which is the slave device bus address; here's a sample:
+        /* For L3 cache PMU */
+        pmul3c0 {
+            compatible = "hisilicon,hisi-pmu-l3c-v1";
+            scl-id = <0x02>;
+            num-events = <0x16>;
+            num-counters = <0x08>;
+            module-id = <0x04>;
+            num-banks = <0x04>;
+            cfgen-map = <0x02 0x04 0x01 0x08>;
+            counter-reg = <0x170>;
+            evctrl-reg = <0x04>;
+            event-en = <0x1000000>;
+            evtype-reg = <0x140>;
+        };

FYI, "module-id" is our own internal hw nomenclature.

Yes, that was my interpretation as well. Please use the standard
"reg" property for this then.

Hi Arnd,

Firstly my apologies for a mistake in the bindings example in ([PATCH
02/11 ..]).
The module-id property is a list as defined in the PMU bindings patch
([PATCH v1 05/11] dt-bindings .. <https://lkml.org/lkml/2016/11/2/323>).

+    djtag0: djtag at 0 {
+        compatible = "hisilicon,hip05-cpu-djtag-v1";
+            pmul3c0 {
+                compatible = "hisilicon,hisi-pmu-l3c-v1";
+                scl-id = <0x02>;
+                num-events = <0x16>;
+                num-counters = <0x08>;
+                module-id = <0x04 0x04 0x04 0x04>;
+                num-banks = <0x04>;
+                cfgen-map = <0x02 0x04 0x01 0x08>;
+                counter-reg = <0x170>;
+                evctrl-reg = <0x04>;
+                event-en = <0x1000000>;
+                evtype-reg = <0x140>;
+            };


The L3 cache in hip05/06/07 chips consist of 4 banks (each bank has PMU
registers).

In hip05/06 all L3 cache banks are identified with same module-id.
module-id = <0x04 0x04 0x04 0x04>;

But in the case hip07 chip(djtag v2), each L3 cache bank has different
module-id
module-id = <0x01 0x02 0x03 0x04>;

So in this case Please share your opinion on how to model it.

My suggestion is to have a single PMU per module, whether that is 4 
banks or 1 bank per module, as this makes the driver simpler.

I think you mentioned that a separate PMU per bank does not make much 
sense, and you would rather treat all banks as a single bank and 
aggregrate their perf statstics under a single PMU: Can you just use a 
script in userspace which can do this aggregration work if you have 
separate PMUs?

Maybe perf guys have a view on this also.

John

Some more detail of L3 cache PMU.
------------------------------------------------
The hip05/06/07 chips consists of a multiple Super CPU cluster (16 CPU
cores). we call it SCCL.
The L3 cache( 4 banks) is shared by all CPU cores in a SCCL.
Each L3 cache bank has PMU registers. We always take the sum of the
counters to show in perf.
Taking individual L3 cache count is not meaningful as there is no
mapping of CPU cores to individual
L3 cache banks.

Please share your suggestion.

Thanks,
Anurup