linux-kernel - Re: [RFC PATCH 6/7] ARM: dts: stm32: add ETZPC as a system bus for STM32MP15x boards

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Message-ID: <0bff5b2d-2837-57cb-5434-58158acc1483@foss.st.com>
Date:   Thu, 22 Dec 2022 15:42:09 +0100
From:   Gatien CHEVALLIER <gatien.chevallier@...s.st.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>,
        <alexandre.torgue@...s.st.com>, <robh+dt@...nel.org>,
        <Oleksii_Moisieiev@...m.com>, <linus.walleij@...aro.org>,
        <gregkh@...uxfoundation.org>
CC:     <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <loic.pallardy@...com>,
        <devicetree@...r.kernel.org>, <mark.rutland@....com>,
        <arnd@...db.de>
Subject: Re: [RFC PATCH 6/7] ARM: dts: stm32: add ETZPC as a system bus for
 STM32MP15x boards

Hello,


On 12/22/22 11:30, Krzysztof Kozlowski wrote:
> On 21/12/2022 18:30, 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.
>>
>> Signed-off-by: Gatien Chevallier <gatien.chevallier@...s.st.com>
>> ---
>>   arch/arm/boot/dts/stm32mp151.dtsi | 2737 +++++++++++++++--------------
>>   1 file changed, 1406 insertions(+), 1331 deletions(-)
>>   
>> -		lptimer1: timer@...09000 {
>> +		etzpc: etzpc@...07000 {
> 
> Node names should be generic.
> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation

Will change to etzpc: bus@...07000 in V3

> 
>> +			compatible = "st,stm32mp15-sys-bus";
>> +			reg = <0x5c007000 0x400>;
>>   			#address-cells = <1>;
>> -			#size-cells = <0>;
>> -			compatible = "st,stm32-lptimer";
>> -			reg = <0x40009000 0x400>;
>> -			interrupts-extended = <&exti 47 IRQ_TYPE_LEVEL_HIGH>;
>> -			clocks = <&rcc LPTIM1_K>;
>> -			clock-names = "mux";
>> -			wakeup-source;
>> -			status = "disabled";
> 
> Why entire bus is disabled? What resources do you miss?

Here, I did not want to modify the status of the nodes in the device 
tree. Nodes that are default enabled in the SoC device tree stay enabled 
and vice-versa. IMO think this patch should not include these kind of 
changes in its scope. I describe the bus and the peripherals connected 
to it, nothing more :)

> 
>> +			#size-cells = <1>;
>> +			feature-domain-controller;
>> +			#feature-domain-cells = <2>;
>> +			ranges;
>>   
> Best regards,
> Krzysztof
> 

Best regards,
Gatien