Hi Conor,

On 25.12.24 15:20, Conor Dooley wrote:

On Thu, Dec 19, 2024 at 09:14:10PM +0100, Ahmad Fatoum wrote:

quoted

On 19.12.24 20:49, Conor Dooley wrote:

quoted

On Thu, Dec 19, 2024 at 08:27:32AM +0100, Ahmad Fatoum wrote:

Theoretically, we could infer mode at runtime from VDD_SOC voltage,
but we need to set up clocks to read out the PMIC and I want to
apply the constraints as early as possible as I don't want the SoC
to run outside of spec even for a short while.

Apologies for the delay responding to you, doing it today cos I feel
guilty!

I am fully aware that I needn't expect prompt review feedback so late in
December. Thanks a lot for taking the time still.

I think what you've explained here is fine, but could you add a
bit more of that info to the commit message, explaining why one cannot
be default? With that,
Acked-by: Conor Dooley <conor.dooley@microchip.com>

Thanks. I will await further review feedback and adjust this commit's
message for v2 as requested.

Wishing you nice holidays,
Ahmad

Cheers,
Conor.

quoted

Thanks,
Ahmad

quoted

quoted

While the overdrive mode allows for higher frequencies for many IPs,
the nominal mode needs a lower SoC voltage, thereby reducing
heat generation and power usage.

In any case, software should respect the maximum clock rate limits
described in the datasheet for each of the two operating modes.

To allow device tree consumers to enforce these limits, document two new
optional properties that can be used to sanity check the clock tree.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 Documentation/devicetree/bindings/clock/imx8m-clock.yaml | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
index c643d4a81478..a6ae5257ef53 100644
--- a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
+++ b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml

@@ -43,6 +43,14 @@ properties:
       ID in its "clocks" phandle cell. See include/dt-bindings/clock/imx8m-clock.h
       for the full list of i.MX8M clock IDs.
 
+  fsl,nominal-mode:
+    description: Set if SoC is operated in nominal mode
+    $ref: /schemas/types.yaml#/definitions/flag
+
+  fsl,overdrive-mode:
+    description: Set if SoC is operated in overdrive mode
+    $ref: /schemas/types.yaml#/definitions/flag
+
 required:
   - compatible
   - reg

@@ -95,6 +103,12 @@ allOf:
             - const: clk_ext2
             - const: clk_ext3
             - const: clk_ext4
+  - if:
+      required:
+        - fsl,overdrive-mode
+    then:
+      properties:
+        fsl,nominal-mode: false
 
 additionalProperties: false
 

-- 
2.39.5

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Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |