Re: [PATCH 7/8] arm64: dts: rockchip: Add SDMMC/SDIO controllers for RK3528

[Jonas Karlman <jonas@kwiboo.se>]

Hi Heiko,

On 2025-03-01 13:55, Heiko Stübner wrote:
> Hey Joas,
> 
> Am Samstag, 1. März 2025, 13:47:47 MEZ schrieb Jonas Karlman:
>> On 2025-03-01 11:47, Yao Zi wrote:
>>> RK3528 features two SDIO controllers and one SD/MMC controller, describe
>>> them in devicetree. Since their sample and drive clocks are located in
>>> the VO and VPU GRFs, corresponding syscons are added to make these
>>> clocks available.
>>>
>>> Signed-off-by: Yao Zi <ziyao@disroot.org>
>>> ---
>>>  arch/arm64/boot/dts/rockchip/rk3528.dtsi | 62 ++++++++++++++++++++++++
>>>  1 file changed, 62 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3528.dtsi b/arch/arm64/boot/dts/rockchip/rk3528.dtsi
>>> index 5b334690356a..078c97fa1d9f 100644
>>> --- a/arch/arm64/boot/dts/rockchip/rk3528.dtsi
>>> +++ b/arch/arm64/boot/dts/rockchip/rk3528.dtsi
>>> @@ -7,6 +7,7 @@
>>>  #include <dt-bindings/interrupt-controller/arm-gic.h>
>>>  #include <dt-bindings/interrupt-controller/irq.h>
>>>  #include <dt-bindings/clock/rockchip,rk3528-cru.h>
>>> +#include <dt-bindings/reset/rockchip,rk3528-cru.h>
>>>  
>>>  / {
>>>  	compatible = "rockchip,rk3528";
>>> @@ -122,6 +123,16 @@ gic: interrupt-controller@fed01000 {
>>>  			#interrupt-cells = <3>;
>>>  		};
>>>  
>>> +		vpu_grf: syscon@ff340000 {
>>> +			compatible = "rockchip,rk3528-vpu-grf", "syscon";
>>
>> vpu_grf is also used for gmac1, so should possible be a "syscon",
>> "simple-mfd", or have I misunderstood when to use simple-mfd ?
> 
> simple-mfd is needed when the additional device is completely contained
> inside the particular syscon.
> 
> For example, the usb2phy0 on rk3588 is completely living inside the
> usb2phy0-grf.
> 
> Similarly the power-domains are living inside the rk3588 pmugrf.
> But the pmugrf also contains more stuff, so the power-domains are a
> subset of the pmugrf.
> 
> Both of these above are a case for a simple-mfd.
> 
> 
> Similarly, gmac1 on rk3588 is ethernet@fe1c0000 , so a completely separate
> io-memory area, but references both the sysgrf as well as the php-grf
> as syscons for additional settings.
> 
> So here the syscon does not need to be a simple-mfd.
> 
> 
> Hope that helps a bit

Thanks for this explanation, it helped me better understand the meaning
of simple-mfd :-)

Regards,
Jonas

> Heiko
> 
>