On Mon, Jan 16, 2017 at 10:59:04AM +0000, Will Deacon wrote:

On Fri, Jan 13, 2017 at 06:43:52PM +0000, Mark Rutland wrote:

quoted

On Fri, Jan 13, 2017 at 04:03:49PM +0000, Will Deacon wrote:

quoted

This patch documents the devicetree binding in use for ARM SPE.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Will Deacon <redacted>
---
 Documentation/devicetree/bindings/arm/spe-pmu.txt | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/spe-pmu.txt

diff --git a/Documentation/devicetree/bindings/arm/spe-pmu.txt b/Documentation/devicetree/bindings/arm/spe-pmu.txt
new file mode 100644
index 000000000000..d6540b491af4
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/spe-pmu.txt

@@ -0,0 +1,20 @@
+* ARMv8.2 Statistical Profiling Extension (SPE) Performance Monitor Units (PMU)
+
+ARMv8.2 introduces the optional Statistical Profiling Extension for collecting
+performance sample data using an in-memory trace buffer.
+
+** SPE Required properties:
+
+- compatible : should be one of:
+	       "arm,arm-spe-pmu-v1"

The second "arm" here doesn't seem to add much. Should that be "armv8.2"
instead?

I don't think armv8.2 is particularly helpful, because that effectively ties
together the SPE version and the architecture version, which I don't think
is strictly required.

Sure; I was mostly going by the example of the generic timer (which
changed somewhat between ARMv7 and ARMv8), but if SPE is somewhat
decoupled from ARMv8.2 that's not a big concern.

The reason I added it was so that you could describe
a partner implementation as something like:

  acme,arm-spe-pmu-v1

and know that it was acme's implementation of an ARM architectural feature.

We don't seem to do this for the SMMU, or elsewhere that I am aware of.

If I drop the second "arm", I was worried that it might conflict with other
namespaces (e.g. acme's signal-processing-element's power-management-unit).

That does sound possible.

Another way of avoiding this would be to expand "spe" (and we can drop
"pmu", since that's not actually part of the SPE name, and implied
anyhow).

How would you feel about:

"arm,statisitical-profiling-extension-v1"

Thanks,
Mark.