linux-kernel - Re: [PATCH v7 2/2] arm64: dts: qcom: talos-evk: Add support for QCS615 talos evk board

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Message-ID: <w6tcgrn7dio3vmygcyhkofg6ie773dppxnk7f3v2kr6rqdufwz@klpqzkojfitk>
Date: Tue, 18 Nov 2025 09:30:16 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Sudarshan Shetty <tessolveupstream@...il.com>
Cc: konradybcio@...nel.org, robh@...nel.org, krzk+dt@...nel.org, 
	conor+dt@...nel.org, linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/2] arm64: dts: qcom: talos-evk: Add support for
 QCS615 talos evk board

On Tue, Nov 18, 2025 at 06:38:14PM +0530, Sudarshan Shetty wrote:
> Add the device tree for the QCS615-based Talos EVK platform. The
> platform is composed of a System-on-Module following the SMARC
> standard, and a Carrier Board.
> 
> The Carrier Board supports several display configurations, HDMI and
> LVDS. Both configurations use the same base hardware, with the display
> selection controlled by a DIP switch.
> 
> To avoid duplication, use an include file, talos-evk-cb.dtsi, which
> defines the interfaces and peripherals common to both display
> variants. Two additional DTs (e.g. talos-evk and talos-evk-lvds)
> can describe the selected display configuration.
> 
> The initial device tree includes support for:
> - CPU and memory
> - UART
> - GPIOs
> - Regulators
> - PMIC
> - Early console
> - AT24MAC602 EEPROM
> - MCP2515 SPI to CAN
> - ADV7535 DSI-to-HDMI bridge
> - DisplayPort interface
> 
> Signed-off-by: Sudarshan Shetty <tessolveupstream@...il.com>
> ---
>  arch/arm64/boot/dts/qcom/Makefile           |   1 +
>  arch/arm64/boot/dts/qcom/talos-evk-cb.dtsi  |  56 +++
>  arch/arm64/boot/dts/qcom/talos-evk-som.dtsi | 447 ++++++++++++++++++++
>  arch/arm64/boot/dts/qcom/talos-evk.dts      |  94 ++++
>  4 files changed, 598 insertions(+)
>  create mode 100644 arch/arm64/boot/dts/qcom/talos-evk-cb.dtsi
>  create mode 100644 arch/arm64/boot/dts/qcom/talos-evk-som.dtsi
>  create mode 100644 arch/arm64/boot/dts/qcom/talos-evk.dts
> 
> diff --git a/arch/arm64/boot/dts/qcom/Makefile b/arch/arm64/boot/dts/qcom/Makefile
> index 5b52f9e4e5f3..282d744acd73 100644
> --- a/arch/arm64/boot/dts/qcom/Makefile
> +++ b/arch/arm64/boot/dts/qcom/Makefile
> @@ -305,6 +305,7 @@ dtb-$(CONFIG_ARCH_QCOM)	+= sm8650-mtp.dtb
>  dtb-$(CONFIG_ARCH_QCOM)	+= sm8650-qrd.dtb
>  dtb-$(CONFIG_ARCH_QCOM)	+= sm8750-mtp.dtb
>  dtb-$(CONFIG_ARCH_QCOM)	+= sm8750-qrd.dtb
> +dtb-$(CONFIG_ARCH_QCOM)	+= talos-evk.dtb
>  x1e001de-devkit-el2-dtbs	:= x1e001de-devkit.dtb x1-el2.dtbo
>  dtb-$(CONFIG_ARCH_QCOM)	+= x1e001de-devkit.dtb x1e001de-devkit-el2.dtb
>  x1e78100-lenovo-thinkpad-t14s-el2-dtbs	:= x1e78100-lenovo-thinkpad-t14s.dtb x1-el2.dtbo
> diff --git a/arch/arm64/boot/dts/qcom/talos-evk-cb.dtsi b/arch/arm64/boot/dts/qcom/talos-evk-cb.dtsi

I might have missed where you replied to any of my questions. But I
still believe this file represents the Talos EVK - that is, the "Talos
SOM" + the "Talos EVK Carrier board".

> new file mode 100644
> index 000000000000..81d15ee4f366
> --- /dev/null
> +++ b/arch/arm64/boot/dts/qcom/talos-evk-cb.dtsi
> @@ -0,0 +1,55 @@
> +// SPDX-License-Identifier: BSD-3-Clause
> +/*
> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> + */
> +/dts-v1/;
> +
> +#include "talos-evk-som.dtsi"

Here this file stops being just a definition of the "carrier board",
it's now the whole EVK.

As such, this file should be called "talos-evk".

We now have two options:

1) talos-som.dtsi + talos-evk.dts + talos-evk-lvds-auo,g133han01.dtso

   We describe the SOM, we describe the "standard configuration" of the
   EVK, and we have an overlay example that disabled the HDMI portions
   and adds LVDS and the specific panel.


2) talos-som.dtsi + talos-evk.dtsi + talos-evk-hdmi.dts +
   talos-evk-lvds.dts + talos-evk-lvds-auo,g133han01.dtso

   We avoid describing HDMI, just to remove it again in the overlay.


#2 would scale better if we have a lot of these boards, but unless we
expect a lot of different boards/combinations I don't think there's much
value in it.


Please let me know if my assumptions are wrong, but for now I think #1
is the correct choice.

In either case, you should include the LVDS support in this same patch
series, so that we have all the parts that we're discussing in front of
us.

> +
> +/ {
> +	model = "Qualcomm QCS615 IQ 615 EVK";
> +	compatible = "qcom,talos-evk", "qcom,qcs615", "qcom,sm6150";
> +	chassis-type = "embedded";
> +
[..]
> diff --git a/arch/arm64/boot/dts/qcom/talos-evk-som.dtsi b/arch/arm64/boot/dts/qcom/talos-evk-som.dtsi
[..]
> +&mdss_dp0_out {
> +	link-frequencies = /bits/ 64 <1620000000 2700000000 5400000000>;
> +	remote-endpoint = <&dp0_connector_in>;

Don't we need/want a data-lanes property here as well?

> +};
> +

The rest of the patch looks good to me.

Regards,
Bjorn