Re: [PATCH v2 2/8] dt-bindings: arm: apple: Add apple,pmgr binding

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On 27/10/2021 23.51, Krzysztof Kozlowski wrote:
On Wed, 27 Oct 2021 at 16:44, Rob Herring <robh@xxxxxxxxxx> wrote:

On Tue, Oct 26, 2021 at 10:38 PM Hector Martin <marcan@xxxxxxxxx> wrote:

On 27/10/2021 03.25, Rob Herring wrote:
On Mon, Oct 25, 2021 at 11:47:12PM +0900, Hector Martin wrote:
+  compatible:
+    items:
+      - enum:
+          - apple,t8103-pmgr
+          - apple,t8103-minipmgr
+      - const: apple,pmgr
+      - const: syscon
+      - const: simple-mfd


'simple-mfd' means 'there's nothing in this node that any of the child
nodes depend on'. You should be somewhat certain as dropping it later
creates compatibility issues.

Hmm, I see simple-mfd turns this into a bus which I guess allows child
nodes to be probed without the parent node doing anything special (then
we use syscon_node_to_regmap to get the syscon instantiated). Do you
have a example use case for doing this without simple-mfd?

Drivers calling of_platform_populate or devm_of_platform_populate.

That of course does mean you need a driver. We could probably make the
syscon driver call these if needed.


Hi Hector,

I thought I mentioned this with your v1, maybe the comment got lost.
We have it for Exynos PMU:
drivers/soc/samsung/exynos-pmu.c
arch/arm/boot/dts/exynos-syscon-restart.dtsi (extending node from
arch/arm/boot/dts/exynos5420.dtsi)
Maybe you can base on that.

Ah, I remember the discrete power domains but I missed this syscon.

I see this is mostly used for poweroff/reboot, which makes sense in this context. For pmgr though, the binding only describes the uniform power state registers, so I think I'm comfortable leaving it as a simple-mfd. Other pmgr sub-blocks will probably end up as separate nodes with different bindings anyway (e.g. whatever I do for the clock muxes, need to see how that ties in with audio which I think is the only consumer so far).

If things get more complicated in future SoCs then we can change how we do it on those, of course :)

--
Hector Martin (marcan@xxxxxxxxx)
Public Key: https://mrcn.st/pub



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