Re: [PATCH 1/6] dt-bindings: clock: imx8m: document nominal/overdrive properties

Ahmad Fatoum
2024-12-26T16:54:39Z

Hi Conor,

On 25.12.24 15:20, Conor Dooley wrote:
> On Thu, Dec 19, 2024 at 09:14:10PM +0100, Ahmad Fatoum wrote:
>> On 19.12.24 20:49, Conor Dooley wrote:
>>> 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.
>
>>
>> Thanks,
>> Ahmad
>>
>>>
>>>>
>>>> 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
>>>>
>>
>>
>> --
>> 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 |

--
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 |