Il 12/07/22 10:37, Krzysztof Kozlowski ha scritto:

On 12/07/2022 10:17, AngeloGioacchino Del Regno wrote:

quoted

Il 06/07/22 17:18, Krzysztof Kozlowski ha scritto:

quoted

On 06/07/2022 14:00, Tinghan Shen wrote:

quoted

Hi Krzysztof,

After discussing your message with our power team,
we realized that we need your help to ensure we fully understand you.

On Mon, 2022-07-04 at 14:38 +0200, Krzysztof Kozlowski wrote:

quoted

On 04/07/2022 12:00, Tinghan Shen wrote:

quoted

Add power domains controller node for mt8195.

Signed-off-by: Weiyi Lu <redacted>
Signed-off-by: Tinghan Shen <redacted>
---
   arch/arm64/boot/dts/mediatek/mt8195.dtsi | 327 +++++++++++++++++++++++
   1 file changed, 327 insertions(+)

diff --git a/arch/arm64/boot/dts/mediatek/mt8195.dtsi b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
index 8d59a7da3271..d52e140d9271 100644
--- a/arch/arm64/boot/dts/mediatek/mt8195.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8195.dtsi

@@ -10,6 +10,7 @@
   #include <dt-bindings/interrupt-controller/irq.h>
   #include <dt-bindings/phy/phy.h>
   #include <dt-bindings/pinctrl/mt8195-pinfunc.h>
+#include <dt-bindings/power/mt8195-power.h>
   
   / {
   	compatible = "mediatek,mt8195";

@@ -338,6 +339,332 @@
   			#interrupt-cells = <2>;
   		};
   
+		scpsys: syscon@10006000 {
+			compatible = "syscon", "simple-mfd";

These compatibles cannot be alone.

the scpsys sub node has the compatible of the power domain driver.
do you suggest that the compatible in the sub node should move to here?

Not necessarily, depends. You have here device node representing system
registers. They need they own compatibles, just like everywhere in the
kernel (except the broken cases...).

Whether this should be compatible of power-domain driver, it depends
what this device node is. I don't know, I don't have your datasheets or
your architecture diagrams...

quoted

quoted

quoted

+			reg = <0 0x10006000 0 0x1000>;
+			#power-domain-cells = <1>;

If it is simple MFD, then probably it is not a power domain provider.
Decide.

this MFD device is the power controller on mt8195.

Then it is not a simple MFD but a power controller. Do not use
"simple-mfd" compatible.

quoted

Some features need
to do some operations on registers in this node. We think that implement
the operation of these registers as the MFD device can provide flexibility
for future use. We want to clarify if you're saying that an MFD device
cannot be a power domain provider.

MFD device is Linuxism, so it has nothing to do here. I am talking only
about simple-mfd. simple-mfd is a simple device only instantiating
children and not providing anything to anyone. Neither to children. This
   the most important part. The children do not depend on anything from
simple-mfd device. For example simple-mfd device can be shut down
(gated) and children should still operate. Being a power domain
controller, contradicts this usually.

If my interpretation of this issue is right, I have pushed a solution for it.
Krzysztof, Matthias, can you please check [1] and give feedback, so that
Tinghan can rewrite this commit ASAP?

Reason is - I need the MT8195 devicetree to be complete to push the remaining
pieces for Tomato Chromebooks, of course.

[1]: https://patchwork.kernel.org/project/linux-mediatek/list/?series=658527

I have two or three similar discussions, so maybe I lost the context,
but I don't understand how your fix is matching real hardware.

In the patchset here, Tinghan claimed that power domain controller is a
child of 10006000. 10006000 is also a power domain controller. This was
explicitly described by the DTS code.

Now you abandon this hierarchy in favor of syscon. If the hierarchy was
correct, your patchset does not match the hardware, so it's a no-go.
Describe the hardware.

However maybe this patch did not make any sense and there is no
relationship parent-child... so what do you guys send here? Bunch of
hacks and work-arounds?

For how I get it, hardware side, the SPM (System Power Manager) resides inside
of the SCPSYS block (consequently, in that iospace).

As Matthias pointed out earlier, SCPSYS provides more functionality, but the
only one that's currently implemented upstream is the System Power Manager,
responsible for managing the MTCMOS (power domains).

In any case, now I'm a little confused on how to proceed, can you please give
some suggestion?

Thanks,
Angelo

Your DTS should reflect the hardware, not some hacks.

Best regards,
Krzysztof