Re: [PATCH 2/7] dt-bindings: devfreq: Add bindings for generic imx buses

On 13.08.2019 17:06, Rob Herring wrote:

On Mon, Aug 12, 2019 at 7:32 PM Leonard Crestez [off-list ref] wrote:

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On 8/12/2019 10:47 PM, Rob Herring wrote:

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On Mon, Aug 12, 2019 at 12:49 PM Leonard Crestez [off-list ref] wrote:

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Add initial dt bindings for the interconnects inside i.MX chips.
Multiple external IPs are involved but SOC integration means the
software controllable interfaces are very similar.

+description: |
+  The i.MX SoC family has multiple buses for which clock frequency (and sometimes
+  voltage) can be adjusted.
+
+  Some of those buses expose register areas mentioned in the memory maps as GPV
+  ("Global Programmers View") but not all. Access to this area might be denied for
+  normal world.
+
+  The buses are based on externally licensed IPs such as ARM NIC-301 and Arteris
+  FlexNOC but DT bindings are specific to the integration of these bus
+  interconnect IPs into imx SOCs.

No need to use the interconnect binding?

The interconnect is represented by a separate "virtual" node which might
not be OK. There was also a recent RFC from samsung which turns devfreq
nodes into interconnect providers:

Is that preferable?

Virtual nodes are not OK.

Then I'll try to make the "interconnect" device probe from a soc driver 
and turn devfreq nodes into interconnect providers backed by this same 
singleton device.

Still separate from this series.

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+required:
+  - compatible
+  - clocks

reg?

This is deliberately optional: for some NICs the GPV register area is
not exposed in the memory map. This is unusual but an accurate
description of the hardware.

Different h/w blocks should have different compatibles. GPV is an Arm
thing and I'd expect FlexNOC to be different.

The imx reference manuals call them both "GPV" though layout is indeed 
quite different (and for FlexNoC it's not even documented).

The h/w blocks do have different compat strings (imx8m-nic and 
imx8m-noc). They have a single binding document because didn't want to 
create two nearly-identical bindings, I assume it would be fine to split 
later if needed.

--
Regards,
Leonard

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