linux-kernel - Re: [PATCH] phy: fsl-imx8mq-usb: change ssc_range value for i.MX8MQ

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Message-ID: <aUVzA+c6V+50TETP@lizhi-Precision-Tower-5810>
Date: Fri, 19 Dec 2025 10:45:07 -0500
From: Frank Li <Frank.li@....com>
To: Xu Yang <xu.yang_2@....com>
Cc: vkoul@...nel.org, neil.armstrong@...aro.org, shawnguo@...nel.org,
	kernel@...gutronix.de, festevam@...il.com, jun.li@....com,
	linux-phy@...ts.infradead.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] phy: fsl-imx8mq-usb: change ssc_range value for i.MX8MQ

On Fri, Dec 19, 2025 at 04:13:54PM +0800, Xu Yang wrote:
> According to IC engineer suggestion, set ssc_range as -4003 ppm
> will have more tolerance for EMI, and suitable for more boards.
> Besides, it's confirmed that with this setting the TX SSC test
> will pass on one customer board.

nit: next time wrap at 75 char.

>
> Signed-off-by: Li Jun <jun.li@....com>
> Signed-off-by: Xu Yang <xu.yang_2@....com>
> ---

Reviewed-by: Frank Li <Frank.Li@....com>

>  drivers/phy/freescale/phy-fsl-imx8mq-usb.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
> index cb2392008ad2..02d9af409b08 100644
> --- a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
> +++ b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
> @@ -18,6 +18,10 @@
>  #define PHY_CTRL0_FSEL_MASK		GENMASK(10, 5)
>  #define PHY_CTRL0_FSEL_24M		0x2a
>  #define PHY_CTRL0_FSEL_100M		0x27
> +#define PHY_CTRL0_SSC_RANGE_MASK	GENMASK(23, 21)
> +#define PHY_CTRL0_SSC_RANGE_4003PPM	0x2
> +#define PHY_CTRL0_SSC_RANGE_4492PPM	0x1
> +#define PHY_CTRL0_SSC_RANGE_4980PPM	0x0
>
>  #define PHY_CTRL1			0x4
>  #define PHY_CTRL1_RESET			BIT(0)
> @@ -780,6 +784,9 @@ static int imx8mq_usb_phy_init(struct phy *phy)
>
>  	value = readl(imx_phy->base + PHY_CTRL0);
>  	value |= PHY_CTRL0_REF_SSP_EN;
> +	value &= ~PHY_CTRL0_SSC_RANGE_MASK;
> +	value |= FIELD_PREP(PHY_CTRL0_SSC_RANGE_MASK,
> +			    PHY_CTRL0_SSC_RANGE_4003PPM);
>  	writel(value, imx_phy->base + PHY_CTRL0);
>
>  	value = readl(imx_phy->base + PHY_CTRL2);
> --
> 2.34.1
>
>
> --
> linux-phy mailing list
> linux-phy@...ts.infradead.org
> https://lists.infradead.org/mailman/listinfo/linux-phy

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