linux-kernel - Re: [PATCH v1 2/4] ARM: dts: rockchip: remove unlikly-to-exist DAC from elgin-r1

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Message-ID: <3870188.FjKLVJYuhi@diego>
Date: Wed, 17 Jul 2024 12:18:08 +0200
From: Heiko Stübner <heiko@...ech.de>
To: linux-kernel@...r.kernel.org, Conor Dooley <conor@...nel.org>,
 Otavio Salvador <otavio@...ystems.com.br>
Cc: conor@...nel.org, Conor Dooley <conor.dooley@...rochip.com>,
 Dinh Nguyen <dinguyen@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>, Huacai Chen <chenhuacai@...nel.org>,
 WANG Xuerui <kernel@...0n.name>, devicetree@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 imx@...ts.linux.dev, loongarch@...ts.linux.dev
Subject:
 Re: [PATCH v1 2/4] ARM: dts: rockchip: remove unlikly-to-exist DAC from
 elgin-r1

adding Otavio,

Am Mittwoch, 17. Juli 2024, 11:37:54 CEST schrieb Conor Dooley:
> From: Conor Dooley <conor.dooley@...rochip.com>
> 
> The Rohm dh2228fv (really the bh2228fv, the compatible in the kernel has
> a typo) does not support frequencies above 10 MHz, nor per the
> datasheet appear to use either CPOL or CPHA. I suspect that this
> devicetree is abusing the compatible in order to bind the spidev driver
> in Linux. Pretending to have devices on a board for this purpose is not
> acceptable, so remove it.

Reasoning is sound, so I'll pick this up after the merge window.


> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
> ---
> I could not find any documentation for this board online, and it does
> not blatantly say that the device is a "spidev" like other [ab]users, so
> it is possible there's actually a DAC here - but I doubt it is a
> bh2228fv given the other incompatibilities.

Otavio, as the original submitter of the Elgin R1 [0], do you happen
to know what type of device this is? Especially as there really do not
seem to be any schematics around for that board.


Heiko



[0] https://patchwork.kernel.org/project/linux-rockchip/patch/20190104014023.17973-4-otavio@ossystems.com.br/

> ---
>  arch/arm/boot/dts/rockchip/rv1108-elgin-r1.dts | 8 --------
>  1 file changed, 8 deletions(-)
> 
> diff --git a/arch/arm/boot/dts/rockchip/rv1108-elgin-r1.dts b/arch/arm/boot/dts/rockchip/rv1108-elgin-r1.dts
> index 2d9994379eb2..9df1cef406c5 100644
> --- a/arch/arm/boot/dts/rockchip/rv1108-elgin-r1.dts
> +++ b/arch/arm/boot/dts/rockchip/rv1108-elgin-r1.dts
> @@ -167,14 +167,6 @@ &spi {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&spim1_clk &spim1_cs0 &spim1_tx &spim1_rx>;
>  	status = "okay";
> -
> -	dh2228fv: dac@0 {
> -		compatible = "rohm,dh2228fv";
> -		reg = <0>;
> -		spi-max-frequency = <24000000>;
> -		spi-cpha;
> -		spi-cpol;
> -	};
>  };
>  
>  &u2phy {
>