Re: [PATCH] arm64: dts: imx8mp: Align both CSI2 pixel clock

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Marek Vasut <marex@denx.de>
Cc: linux-arm-kernel@lists.infradead.org,
	Conor Dooley <conor+dt@kernel.org>,
	Fabio Estevam <festevam@gmail.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Paul Elder <paul.elder@ideasonboard.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Rob Herring <robh@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Shawn Guo <shawnguo@kernel.org>,
	devicetree@vger.kernel.org, imx@lists.linux.dev,
	Adam Ford <aford173@gmail.com>
Subject: Re: [PATCH] arm64: dts: imx8mp: Align both CSI2 pixel clock
Date: Fri, 5 Apr 2024 23:42:51 +0300	[thread overview]
Message-ID: <20240405204251.GE12507@pendragon.ideasonboard.com> (raw)
In-Reply-To: <20240405202243.46278-1-marex@denx.de>

Hi Marek,

(CC'ing Adam)

Thank you for the patch.

On Fri, Apr 05, 2024 at 10:22:26PM +0200, Marek Vasut wrote:
> Configure both CSI2 assigned-clock-rates the same way.
> There does not seem to be any reason for keeping the
> two CSI2 pixel clock set to different frequencies.

There's an issue when using two cameras concurrently. This has been
discussed some time ago on the linux-media mailing list, see [1]. Adam
knows more than I do on this topic.

[1] https://lore.kernel.org/linux-media/CAHCN7x+kymRGO2kxvN2=zLiqRjfTc3hdf3VdNVkWjsW3La0bnA@mail.gmail.com/

> Signed-off-by: Marek Vasut <marex@denx.de>
> ---
> Cc: Conor Dooley <conor+dt@kernel.org>
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Paul Elder <paul.elder@ideasonboard.com>
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: devicetree@vger.kernel.org
> Cc: imx@lists.linux.dev
> Cc: linux-arm-kernel@lists.infradead.org
> ---
>  arch/arm64/boot/dts/freescale/imx8mp.dtsi | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> index 1bb96e96639f2..2e9ce0c3a9815 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> @@ -1703,7 +1703,7 @@ mipi_csi_1: csi@32e50000 {
>  						  <&clk IMX8MP_CLK_MEDIA_MIPI_PHY1_REF>;
>  				assigned-clock-parents = <&clk IMX8MP_SYS_PLL2_1000M>,
>  							 <&clk IMX8MP_CLK_24M>;
> -				assigned-clock-rates = <266000000>;
> +				assigned-clock-rates = <500000000>;
>  				power-domains = <&media_blk_ctrl IMX8MP_MEDIABLK_PD_MIPI_CSI2_2>;
>  				status = "disabled";
>  

-- 
Regards,

Laurent Pinchart