linux-kernel - Re: [PATCH] phy: fsl-imx8mq-usb: enable RxTermination_override

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Message-ID: <aUV0vn2VPWKAh5f7@lizhi-Precision-Tower-5810>
Date: Fri, 19 Dec 2025 10:52:30 -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: enable RxTermination_override_sel

On Fri, Dec 19, 2025 at 04:30:04PM +0800, Xu Yang wrote:
> This is to resolve the problem of wakeup system by USB3 device
> insertion if HSIOMIX on, in that case, the USB3 device detects

Do you means USB3 device wrong regconized as USB2?

> RX term on so doesn't downgrade to USB2, so DP/DM wakeup can't
> happen, with this override bit we can force the RX term off when
> enters system suspend, and disable the override after system resume.

Enable RxTermination_override_sel to resolve the problem, which wrong
regongized as USB 2.0 device if USB3 device plug-in when HSIOMIX ON.

No clear why force RX term Off can resolve problem. Please rephrase it.

Frank

>
> Signed-off-by: Li Jun <jun.li@....com>
> Signed-off-by: Xu Yang <xu.yang_2@....com>
> ---
>  drivers/phy/freescale/phy-fsl-imx8mq-usb.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
> index 02d9af409b08..0831ed465775 100644
> --- a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
> +++ b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
> @@ -52,6 +52,7 @@
>  #define PHY_CTRL5_PCS_TX_SWING_FULL_MASK	GENMASK(6, 0)
>
>  #define PHY_CTRL6			0x18
> +#define PHY_CTRL6_RXTERM_OVERRIDE_SEL	BIT(29)
>  #define PHY_CTRL6_ALT_CLK_EN		BIT(1)
>  #define PHY_CTRL6_ALT_CLK_SEL		BIT(0)
>
> @@ -847,6 +848,7 @@ static int imx8mp_usb_phy_init(struct phy *phy)
>  static int imx8mq_phy_power_on(struct phy *phy)
>  {
>  	struct imx8mq_usb_phy *imx_phy = phy_get_drvdata(phy);
> +	u32 value;
>  	int ret;
>
>  	ret = regulator_enable(imx_phy->vbus);
> @@ -863,12 +865,23 @@ static int imx8mq_phy_power_on(struct phy *phy)
>  		return ret;
>  	}
>
> -	return ret;
> +	/* Disable rx term override */
> +	value = readl(imx_phy->base + PHY_CTRL6);
> +	value &= ~PHY_CTRL6_RXTERM_OVERRIDE_SEL;
> +	writel(value, imx_phy->base + PHY_CTRL6);
> +
> +	return 0;
>  }
>
>  static int imx8mq_phy_power_off(struct phy *phy)
>  {
>  	struct imx8mq_usb_phy *imx_phy = phy_get_drvdata(phy);
> +	u32 value;
> +
> +	/* Override rx term to be 0 */
> +	value = readl(imx_phy->base + PHY_CTRL6);
> +	value |= PHY_CTRL6_RXTERM_OVERRIDE_SEL;
> +	writel(value, imx_phy->base + PHY_CTRL6);
>
>  	clk_disable_unprepare(imx_phy->alt_clk);
>  	clk_disable_unprepare(imx_phy->clk);
> --
> 2.34.1
>