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

From: "Heiko Stübner" <heiko@sntech.de>
To: linux-kernel@vger.kernel.org, Conor Dooley <conor@kernel.org>,
	Otavio Salvador <otavio@ossystems.com.br>
Cc: conor@kernel.org, Conor Dooley <conor.dooley@microchip.com>,
	Dinh Nguyen <dinguyen@kernel.org>, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	Huacai Chen <chenhuacai@kernel.org>,
	WANG Xuerui <kernel@xen0n.name>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, imx@lists.linux.dev,
	loongarch@lists.linux.dev
Subject: Re: [PATCH v1 2/4] ARM: dts: rockchip: remove unlikly-to-exist DAC from elgin-r1
Date: Wed, 17 Jul 2024 12:18:08 +0200	[thread overview]
Message-ID: <3870188.FjKLVJYuhi@diego> (raw)
In-Reply-To: <20240717-parrot-malt-83cc04bf6b36@spud>

adding Otavio,

Am Mittwoch, 17. Juli 2024, 11:37:54 CEST schrieb Conor Dooley:
> From: Conor Dooley <conor.dooley@microchip.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@microchip.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 {
> 