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Subject: Re: [PATCH 11/13] ARM: dts: stm32: fix LTDC port node on STM32 MCU ad
 MPU
To:     Marek Vasut <marex@denx.de>, <arnd@arndb.de>, <robh+dt@kernel.org>,
        <jagan@amarulasolutions.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        Marcin Sloniewski <marcin.sloniewski@gmail.com>,
        Ahmad Fatoum <a.fatoum@pengutronix.de>
CC:     <linux-arm-kernel@lists.infradead.org>,
        <devicetree@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-kernel@vger.kernel.org>, Lee Jones <lee.jones@linaro.org>,
        <kuba@kernel.org>
References: <20210415101037.1465-1-alexandre.torgue@foss.st.com>
 <20210415101037.1465-12-alexandre.torgue@foss.st.com>
 <3b39908b-a263-a5d4-f6ac-ac30ffb06269@denx.de>
From:   Alexandre TORGUE <alexandre.torgue@foss.st.com>
Message-ID: <36e9f0df-dfdb-e2f5-3d6e-ac32a1b8156e@foss.st.com>
Date:   Thu, 15 Apr 2021 15:34:06 +0200
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Hi Marek

On 4/15/21 3:21 PM, Marek Vasut wrote:
> On 4/15/21 12:10 PM, Alexandre Torgue wrote:
>> Running "make dtbs_check W=1", some warnings are reported concerning
>> LTDC port subnode:
>>
>> /soc/display-controller@5a001000/port:
>> unnecessary #address-cells/#size-cells without "ranges" or child "reg"
>> property
>> /soc/display-controller@5a001000/port: graph node has single child node
>> 'endpoint', #address-cells/#size-cells are not necessary
> 
> btw could you retain diffstat on your patches ? It's useful to see which 
> files changed right away.
> [...]
> 
>> diff --git a/arch/arm/boot/dts/stm32mp157c-dk2.dts 
>> b/arch/arm/boot/dts/stm32mp157c-dk2.dts
>> index 2bc92ef3aeb9..19ef475a48fc 100644
>> --- a/arch/arm/boot/dts/stm32mp157c-dk2.dts
>> +++ b/arch/arm/boot/dts/stm32mp157c-dk2.dts
>> @@ -82,9 +82,15 @@
>>   };
>>   &ltdc {
>> -    status = "okay";
>> -
>>       port {
>> +        #address-cells = <1>;
>> +        #size-cells = <0>;
>> +
>> +        ltdc_ep0_out: endpoint@0 {
>> +            reg = <0>;
>> +            remote-endpoint = <&sii9022_in>;
>> +        };
>> +
>>           ltdc_ep1_out: endpoint@1 {
>>               reg = <1>;
>>               remote-endpoint = <&dsi_in>;
> 
> [...]
> 
>> diff --git a/arch/arm/boot/dts/stm32mp15xx-dhcor-avenger96.dtsi 
>> b/arch/arm/boot/dts/stm32mp15xx-dhcor-avenger96.dtsi
>> index 64dca5b7f748..e7f10975cacf 100644
>> --- a/arch/arm/boot/dts/stm32mp15xx-dhcor-avenger96.dtsi
>> +++ b/arch/arm/boot/dts/stm32mp15xx-dhcor-avenger96.dtsi
>> @@ -277,11 +277,7 @@
>>       status = "okay";
>>       port {
>> -        #address-cells = <1>;
>> -        #size-cells = <0>;
>> -
>> -        ltdc_ep0_out: endpoint@0 {
>> -            reg = <0>;
>> +        ltdc_ep0_out: endpoint {
>>               remote-endpoint = <&adv7513_in>;
>>           };
>>       };
> 
> I think this is wrong, the AV96 can have two displays connected to two 
> ports of the LTDC, just like DK2 for example.

As for dk2 address/size cells are added only if there are 2 endpoints. 
It is for this reason I moved endpoint0 definition from stm32mp15xx-dkx 
to stm32mp151a-dk1.dts (dk1 has only one endpoint).

Here it's the same, if you have second endpoint then adress/size will 
have to be added.

alex