Re: [PATCH v3 5/6] ARM: dts: stm32: add ETZPC as a system bus for STM32MP15x boards

Uwe Kleine-König
2023-02-09T07:52:31Z

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Hello,

On Fri, Jan 27, 2023 at 05:40:39PM +0100, Gatien Chevallier wrote:
> The STM32 System Bus is an internal bus on which devices are connected.
> ETZPC is a peripheral overseeing the firewall bus that configures
> and control access to the peripherals connected on it.
>
> For more information on which peripheral is securable, please read
> the STM32MP15 reference manual.

it might be naive, but I somehow expected that when showing at the
resulting commit with git show -b that the patch gets quite small.

Is it really intended that &etzpc (which has reg = <0x5c007000 0x400>;)
is the parent bus of the devices with feature-domains = <&etzpc XX>; even
though their addresses are out of &etzpc's range? Doesn't a bus usually
have a ranges property and a base address that matches its contained
devices?

Looking at imx6qdl.dtsi there is:

aips1: bus@2000000 { /* AIPS1 */
...
reg = <0x02000000 0x100000>;
ranges;

spba-bus@2000000 {
...
reg = <0x02000000 0x40000>;
...
};

...

sdma: dma-controller@20ec000 {
...
reg = <0x020ec000 0x4000>;
...
};
};

and the registers configuring the aips1 bus are (I think) in

aipstz@207c000 { /* AIPSTZ1 */
reg = <0x0207c000 0x4000>;
};

Maybe this change could be made less intrusive by using a similar setup
here?

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |

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