Re: [PATCH v2] dts: arm64: add CoreSight trace support for hi3660

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Hi,

On 04/03/2019 17:18, Mathieu Poirier wrote:
On Sat, 2 Mar 2019 at 06:00, Leo Yan <leo.yan@xxxxxxxxxx> wrote:

On Sat, Mar 02, 2019 at 09:45:22AM +0000, Shiwanglai wrote:

[...]

+           /* Top internals */
+           funnel@ec031000 {
+                   compatible = "arm,coresight-funnel", "arm,primecell";
+                   reg = <0 0xec031000 0 0x1000>;
+                   clocks = <&crg_ctrl HI3660_PCLK>;
+                   clock-names = "apb_pclk";
+
+                   out-ports {
+                           port {
+                                   top_funnel_out: endpoint {
+                                           remote-endpoint =
+                                                   <&top_etf_in>;
+                                   };
+                           };
+                   };
+
+                   in-ports {
+                           #address-cells = <1>;
+                           #size-cells = <0>;
+
+                           port@0 {
+                                   reg = <0>;
+                                   top_funnel_in0: endpoint {
+                                           remote-endpoint =
+                                                   <&cluster0_etf_out>;
+                                   };
+                           };
+
+                           port@1 {
+                                   reg = <0>;

Here should s/<0>/<1>; otherwise DTC will complain warning for mismatching between 'port@1' and 'reg = <0>'.

-- if reg set to 1, then there's no data output from cluster 1 to top.

Thanks for the info, Wanglai.  Now I see why write as it is.

I can confirm if directly use your patch with perf with mainline
kernel I can capture CoreSight trace data successfully on Hikey960
board.

But since this DT binding will introduce DTC warning, I personally
think we can improve for this with below method:

We can create a funnel node named "funnel_combo", and we don't need to
specify register address range for it; and cluster 0 and cluster 1 will
output to "funnel_combo" and "funnel_combo" will output to the top
funnel.  Thus the DT binding will write as below.

To support for a funnel without any register address range (we have
support replicator like this mode), we also need to extend the driver
drivers/hwtracing/coresight/coresight-funnel.c.

Mathieu, Mike, Suzuki, could you help confirm this is the right
direction we should move forward to?

Leo, thanks for testing this out.  Shiwanglai, please add Suzuki and
myself to future revision of this set - this will help you getting a
timely response for your work.

As Leo pointed out we already have support for replicators that don't
have a register map and the same thing should be done in this case.
But contrary to what was done for replicators, I think we should keep
the drivers in the same file as Russell did here[1].  That way we can
keep all things funnel at the same place and reduce the amount of
kernel configuration options.

I back that. I have already merged the static and programmable replicators
into one and this should be out here soon. So, I back the single driver
approach for funnels.

Cheers
Suzuki



Regards,
Mathieu

[1]. https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/amba-pl011.c#L2819





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