Re: [PATCH v1] arm64: dts: qcom: talos-evk: Add ADV7535 DSI-to-HDMI bridge

[Tessolve Upstream <tessolveupstream@gmail.com>]

On 17/10/25 18:22, Dmitry Baryshkov wrote:
> On Thu, Oct 16, 2025 at 02:24:40PM +0530, Tessolve Upstream wrote:
>>
>>
>> On 15/10/25 18:34, Dmitry Baryshkov wrote:
>>> On Wed, Oct 15, 2025 at 05:58:08PM +0530, Sudarshan Shetty wrote:
>>>> Hook up the ADV7535 DSI-to-HDMI bridge on the QCS615 Talos EVK board.
>>>> This provides HDMI output through the external DSI-to-HDMI converter.
>>>>
>>>> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
>>>> ---
>>>>  arch/arm64/boot/dts/qcom/talos-evk-som.dtsi | 21 ++++++
>>>>  arch/arm64/boot/dts/qcom/talos-evk.dts      | 76 +++++++++++++++++++++
>>>>  2 files changed, 97 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/qcom/talos-evk-som.dtsi b/arch/arm64/boot/dts/qcom/talos-evk-som.dtsi
>>>> index 55ec8034103d..b58cae02c9cb 100644
>>>> --- a/arch/arm64/boot/dts/qcom/talos-evk-som.dtsi
>>>> +++ b/arch/arm64/boot/dts/qcom/talos-evk-som.dtsi
>>>> @@ -244,6 +244,27 @@ eeprom@5f {
>>>>  	};
>>>>  };
>>>>  
>>>> +&mdss {
>>>> +	status = "okay";
>>>> +};
>>>> +
>>>> +&mdss_dsi0 {
>>>> +	vdda-supply = <&vreg_l11a>;
>>>> +
>>>> +	status = "okay";
>>>> +};
>>>> +
>>>> +&mdss_dsi0_out {
>>>> +	remote-endpoint = <&adv7535_in>;
>>>> +	data-lanes = <0 1 2 3>;
>>>> +};
>>>> +
>>>> +&mdss_dsi0_phy {
>>>> +	vdds-supply = <&vreg_l5a>;
>>>> +
>>>> +	status = "okay";
>>>> +};
>>>> +
>>>>  &pcie {
>>>>  	perst-gpios = <&tlmm 101 GPIO_ACTIVE_LOW>;
>>>>  	wake-gpios = <&tlmm 100 GPIO_ACTIVE_HIGH>;
>>>> diff --git a/arch/arm64/boot/dts/qcom/talos-evk.dts b/arch/arm64/boot/dts/qcom/talos-evk.dts
>>>> index 25057f4f6a91..f7e8be3667d1 100644
>>>> --- a/arch/arm64/boot/dts/qcom/talos-evk.dts
>>>> +++ b/arch/arm64/boot/dts/qcom/talos-evk.dts
>>>> @@ -14,6 +14,82 @@ / {
>>>>  	aliases {
>>>>  		mmc1 = &sdhc_2;
>>>>  	};
>>>> +
>>>> +	hdmi-out {
>>>> +		compatible = "hdmi-connector";
>>>> +		type = "d";
>>>> +
>>>> +		port {
>>>> +			hdmi_con_out: endpoint {
>>>> +				remote-endpoint = <&adv7535_out>;
>>>> +			};
>>>> +		};
>>>> +	};
>>>> +
>>>> +	vreg_v1p2_out: regulator-v1p2-out {
>>>> +		compatible = "regulator-fixed";
>>>> +		regulator-name = "vreg-v1p2-out";
>>>> +		regulator-min-microvolt = <1200000>;
>>>> +		regulator-max-microvolt = <1200000>;
>>>> +		regulator-boot-on;
>>>> +		regulator-always-on;
>>>> +	};
>>>> +
>>>> +	vreg_v1p8_out: regulator-v1p8-out {
>>>> +		compatible = "regulator-fixed";
>>>> +		regulator-name = "vreg-v1p8-out";
>>>> +		regulator-min-microvolt = <1800000>;
>>>> +		regulator-max-microvolt = <1800000>;
>>>> +		regulator-boot-on;
>>>> +		regulator-always-on;
>>>> +	};
>>>> +
>>>> +	vreg_v3p3_out: regulator-v3p3-out {
>>>> +		compatible = "regulator-fixed";
>>>> +		regulator-name = "vreg-v3p3-out";
>>>> +		regulator-min-microvolt = <3300000>;
>>>> +		regulator-max-microvolt = <3300000>;
>>>> +		regulator-boot-on;
>>>> +		regulator-always-on;
>>>> +	};
>>>
>>> Please describe the power grid. Are these regulators being fed by
>>> nothing and generating energy from the thin air?
>>
>> Thanks for the feedback.
>> You are right — in the previous patch, the regulators appeared
>> to have no source, which was incorrect.
>>
>> To clarify the hardware design:
>> The 3.3 V and 1.8 V supplies to the HDMI controller are not coming 
>> from the PMIC. They are generated on the carrier board as follows:
>>
>> 20 V (USBC_VBUS_IN) → 5 V rail (V5P0_OUT)
>> → 3.3 V buck regulator (RAA211250) and 1.8 V LDO (TPS7A9101).
>>
>> The 5 V rail (V5P0_OUT) acts as the input supply for both regulators.
>> Both regulators are always on.
>>
>> example:
>> v5p0_out: regulator-v5p0-out {
>>     compatible = "regulator-fixed";
>>     regulator-name = "v5p0_out";
>>     regulator-min-microvolt = <5000000>;
>>     regulator-max-microvolt = <5000000>;
>>     regulator-always-on;
>>     regulator-boot-on;
>> };
>>
>> v3p3_out: regulator-v3p3-out {
>>     compatible = "regulator-fixed";
>>     regulator-name = "v3p3_out";
>>     regulator-min-microvolt = <3300000>;
>>     regulator-max-microvolt = <3300000>;
>>     vin-supply = <&v5p0_out>;
>>     regulator-always-on;
>>     regulator-boot-on;
>> };
>>
>> v1p8_out: regulator-v1p8-out {
>>     compatible = "regulator-fixed";
>>     regulator-name = "v1p8_out";
>>     regulator-min-microvolt = <1800000>;
>>     regulator-max-microvolt = <1800000>;
>>     vin-supply = <&v5p0_out>;
>>     regulator-always-on;
>>     regulator-boot-on;
>> };
>>
>> These reflect the actual power grid of the board.
>> The 20 V input is not modeled since it’s a raw external
>> supply and not managed by Linux.
>>
>> Please let me know if this structure looks acceptable,
>> Thanks again for the review and guidance!
> 
> I think this is perfectly fine, especially if you add the "powered by
> system 20V rail" comment to the 5V regulator.

Thanks!
Will update in v2 patch.
> 
>>>
>>>> +};
>>>> +
>>>> +&i2c1 {
>>>> +	clock-frequency = <400000>;
>>>> +
>>>> +	status = "okay";
>>>> +
>>>> +	adv7535: adv7535@3d {
>>>> +		compatible = "adi,adv7535";
>>>> +		reg = <0x3d>;
>>>> +		avdd-supply = <&vreg_v1p8_out>;
>>>> +		dvdd-supply = <&vreg_v1p8_out>;
>>>> +		pvdd-supply = <&vreg_v1p8_out>;
>>>> +		a2vdd-supply = <&vreg_v1p8_out>;
>>>> +		v3p3-supply = <&vreg_v3p3_out>;
>>>> +		v1p2-supply = <&vreg_v1p2_out>;
>>>
>>> I think this is not correct. Please consult your schematics isntead of
>>> adding dummy regulators.
>>
>> Will take care in v2 patch.
>>>
>>>
>>
>