Re: [PATCH 2/2] ARM: dts: imx6qdl: support child mfd cells for the reset controller

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Krzysztof,

On 16.01.23 09:20, Krzysztof Kozlowski wrote:
> On 13/01/2023 18:32, Bastian Krause wrote:
>> The actual syscon-reboot-mode child node can be added by a board
>> device-tree or fixed up by the bootloader. For the child node to be
>> probed, the compatible needs to include simple-mfd. The binding now
>> specifies this, so have the SoC dtsi adhere to it.
>>
>> Suggested-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>> Signed-off-by: Bastian Krause <bst@pengutronix.de>
>> ---
>>  arch/arm/boot/dts/imx6qdl.dtsi | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/boot/dts/imx6qdl.dtsi b/arch/arm/boot/dts/imx6qdl.dtsi
>> index ff1e0173b39be..b16be39458aa6 100644
>> --- a/arch/arm/boot/dts/imx6qdl.dtsi
>> +++ b/arch/arm/boot/dts/imx6qdl.dtsi
>> @@ -865,7 +865,8 @@ epit2: epit@20d4000 { /* EPIT2 */
>>  			};
>>  
>>  			src: reset-controller@20d8000 {
>> -				compatible = "fsl,imx6q-src", "fsl,imx51-src";
>> +				compatible = "fsl,imx6q-src", "fsl,imx51-src",
>> +					     "syscon", "simple-mfd";
> 
> You need children here. Otherwise simple-mfd does not make sense. If you
> expect something else to add children (I don't understand why, usually
> reboot capability is fixed per SoC and only sometimes extended with some
> other means), then this "else" will also change compatible.

It's about syscon-reboot-mode, not syscon-reboot. Such modes are board-
not soc-specific. Yes, a board DTS can override a compatible, but this
is error prone as you can't just add a compatible, you need to hardcode
the other compatibles in the SoC dtsi, which may change for good reason
in future. barebox supports fixing up syscon-reboot-mode nodes defined
in its own device tree to the Linux DT. While in theory, it could check
if the parent node contains syscon/simple-mfd and fix it up if necessary,
it sounds to me like this should be rather part of the upstream DT.

Cheers,
Ahmad

> 
> Best regards,
> Krzysztof
> 
> 

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