Hi Linu
On Fri, 29 Sept 2023 at 14:38, Linu Cherian <lcherian@xxxxxxxxxxx> wrote:
>
> memory-region 0: Reserved trace buffer memory
>
> TMC ETR: When available, use this reserved memory region for
> trace data capture. Same region is used for trace data
> retention after a panic or watchdog reset.
>
> TMC ETF: When available, use this reserved memory region for
> trace data retention synced from internal SRAM after a panic or
> watchdog reset.
>
> memory-region 1: Reserved meta data memory
>
> TMC ETR, ETF: When available, use this memory for register
> snapshot retention synced from hardware registers after a panic
> or watchdog reset.
>
> Signed-off-by: Linu Cherian <lcherian@xxxxxxxxxxx>
> ---
> .../bindings/arm/arm,coresight-tmc.yaml | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml b/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml
> index cb8dceaca70e..45ca4d02d73e 100644
> --- a/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml
> +++ b/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml
> @@ -101,6 +101,22 @@ properties:
> and ETF configurations.
> $ref: /schemas/graph.yaml#/properties/port
>
> + memory-region:
> + items:
> + - description: Reserved trace buffer memory for ETR and ETF sinks.
> + For ETR, this reserved memory region is used for trace data capture.
> + Same region is used for trace data retention as well after a panic
> + or watchdog reset.
> + For ETF, this reserved memory region is used for retention of trace
> + data synced from internal SRAM after a panic or watchdog reset.
> +
Is there a valid use case for ETR where we use these areas when there
is not a panic/reset situation?
Either way - the description should perhaps mention that these areas
are only used if specifically selected by the driver - the default
memory usage models for ETR / perf are otherwise unaltered.
> + - description: Reserved meta data memory. Used for ETR and ETF sinks.
> +
> + memory-region-names:
> + items:
> + - const: trace-mem
> + - const: metadata-mem
> +
Is there a constraint required here? If we are using the memory area
for trace in a panic situation, then we must have the meta data memory
area defined?
Perhaps a set of names such as "etr-trace-mem", "panic-trace-mem" ,
"panic-metadata-mem", were the first is for general ETR trace in
non-panic situation and then constrain the "panic-" areas to appear
together.
The "etr-trace-mem", "panic-trace-mem" could easily point to the same area.
> required:
> - compatible
> - reg
> @@ -115,6 +131,9 @@ examples:
> etr@20070000 {
> compatible = "arm,coresight-tmc", "arm,primecell";
> reg = <0x20070000 0x1000>;
> + memory-region = <&etr_trace_mem_reserved>,
> + <&etr_mdata_mem_reserved>;
> + memory-region-names = "trace-mem", "metadata-mem";
>
> clocks = <&oscclk6a>;
> clock-names = "apb_pclk";
> --
> 2.34.1
>
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK
