Re: [PATCH 2/3] power: sequencing: Add Renesas RZ/G3L Power Ready driver

On Tue, 28 Jul 2026 13:55:22 +0200, Biju Das <[email protected]> said:
> Hi Bartosz Golaszewski,
>
>> -----Original Message-----
>> From: Bartosz Golaszewski <[email protected]>
>> Sent: 28 July 2026 12:35
>> Subject: Re: [PATCH 2/3] power: sequencing: Add Renesas RZ/G3L Power Ready driver
>>
>> On Tue, 28 Jul 2026 11:17:58 +0200, Biju Das <[email protected]> said:
>> > Hi Bartosz Golaszewski,
>> >
>> > Thanks for the feedback.
>> >
>>
>> ...
>>
>> >> > +
>> >> > +static int pwrseq_rzg3l_pwrrdy_match(struct pwrseq_device *pwrseq,
>> >> > +				     struct device *dev)
>> >> > +{
>> >> > +	return PWRSEQ_MATCH_OK;
>> >>
>> >> When I see an always-tru match() callback, it always raises an alarm bell.
>> >> Typically, I'd expect there to be some validation of the consumer happening.
>> >>
>> >> Please at least provide an explanation of why it's ok.
>> >
>> > Without the match function the driver is not probing.
>> >
>>
>> Yes, that's expected.
>>
>> > sysc(driver) ->powerseq(driver) ->{DSI,CSI,USB}(driver) there is no
>> > property that I can match here as the resource is a register on the
>> > SYSC IP and powerseq driver is instantiated by the SYSC driver.
>> >
>> > Maybe I can provide a comment here saying that??
>> > "No DT property to match here, so it is OK always"
>> >
>>
>> So the sysc is the parent of the pwrseq provider and the CSI, DSI and USB drivers are the consumers of
>> the pwrseq descriptor? The latter are children of the platform bus, am I getting this right? Can you
>> point me to the device tree that describes it?
>
> Yes,
>
> Please see [1], [2], [3]
>
> [1] sysc node
>
> [2] phyrst node (I planned to remove renesas,sysc-pwrrdy in the next version as it is going to use pwrseq)
>
> [3] dsi node (I planned to remove renesas,sysc-pwrrdy in the next version as it is going to use pwrseq)
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm64/boot/dts/renesas/r9a08g046.dtsi?h=next-20260727#n609
>
> [2] https://lore.kernel.org/all/TY3PR01MB11346FA21EFADC8A3D53D81BE86CF2@TY3PR01MB11346.jpnprd01.prod.outlook.com/T/#mf24ae1363925a97c840b275c108a9b72942c40bc
>
> [3] https://lore.kernel.org/all/[email protected]/T/#m31c6711b5403c5a387b22467bb88371df73ae2b1
>
>
> Cheers,
> Biju
>

Then it seems you have a phandle from the DSI node to the sysc node:

renesas,sysc-pwrrdy = <&sysc 0xd70 0x2>;

In match() you can check if that phandle leads to the sysc device who's the
parent of the power sequencer device and return MATCH_OK if it is.

Bart