Re: [PATCH] usb: phy: mxs: manually reset phy regs after a warm reset

[Frank Li]

On Mon, Mar 30, 2026 at 05:31:33PM +0800, Xu Yang wrote:
> The usb phy registers are not fully reset on warm reset under stress
> conditions. We need to manually reset those (CTRL, PWD, DEBUG, PLL_SIC)

Avoid the words "we ..."

So need manually reset CTRL, PWD, DEBUG, PLL_SIC ...

> regs after a warm reset. This will reset DEBUG and PLL_SIC registers.
> CTRL and PWD register are handled by "SFT" bit in stmp_reset_block().
>
> ERR051269: USB PHY registers not fully resetting on warm reset under
>            stress conditions
>
> The following USB PHY registers must be written by SW to restore the reset
> value after a warm reset:
>
> Reg: ctrl Addr: 0x29910030 Data: 0xc000_0000
> Reg: pwd Addr: 0x29910000 Data: 0x001e_1c00
> Reg: debug0 Addr: 0x29910050 Data: 0x7f18_0000
> Reg: pll_sic Addr: 0x299100a0 Data: 0x00d1_2000
>
> Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>
> ---
>  drivers/usb/phy/phy-mxs-usb.c | 32 +++++++++++++++++++++++++++++---
>  1 file changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/phy/phy-mxs-usb.c b/drivers/usb/phy/phy-mxs-usb.c
> index 7069dd3f4d0d..dd42db8a0829 100644
> --- a/drivers/usb/phy/phy-mxs-usb.c
> +++ b/drivers/usb/phy/phy-mxs-usb.c
> @@ -209,6 +209,9 @@ static const struct mxs_phy_data imx6ul_phy_data = {
>  static const struct mxs_phy_data imx7ulp_phy_data = {
>  };
>
> +static const struct mxs_phy_data imx8ulp_phy_data = {
> +};
> +
>  static const struct of_device_id mxs_phy_dt_ids[] = {
>  	{ .compatible = "fsl,imx6sx-usbphy", .data = &imx6sx_phy_data, },
>  	{ .compatible = "fsl,imx6sl-usbphy", .data = &imx6sl_phy_data, },
> @@ -217,6 +220,7 @@ static const struct of_device_id mxs_phy_dt_ids[] = {
>  	{ .compatible = "fsl,vf610-usbphy", .data = &vf610_phy_data, },
>  	{ .compatible = "fsl,imx6ul-usbphy", .data = &imx6ul_phy_data, },
>  	{ .compatible = "fsl,imx7ulp-usbphy", .data = &imx7ulp_phy_data, },
> +	{ .compatible = "fsl,imx8ulp-usbphy", .data = &imx8ulp_phy_data, },
>  	{ /* sentinel */ }
>  };
>  MODULE_DEVICE_TABLE(of, mxs_phy_dt_ids);
> @@ -248,6 +252,11 @@ static inline bool is_imx7ulp_phy(struct mxs_phy *mxs_phy)
>  	return mxs_phy->data == &imx7ulp_phy_data;
>  }
>
> +static inline bool is_imx8ulp_phy(struct mxs_phy *mxs_phy)
> +{
> +	return mxs_phy->data == &imx8ulp_phy_data;

don't use this kind check.

Add field 'need_reset_reg' in mxs_phy_data

imx8ulp_phy_data = {
	.need_reset_reg = true;
}

if (mxs->data->need_reset_reg)
	...

The same logic for
	if (is_imx7ulp_phy(mxs_phy) || is_imx8ulp_phy(mxs_phy))
		mxs_phy_pll_enable(phy->io_priv, false);

add 'need_phy_pull_enable' in mxs_phy_data. (new patch for it)
    set it true at both imx7ulp_phy_data and imx8ulp_phy_data.

Frank

> +}
> +
>  static inline bool is_imx6ul_phy(struct mxs_phy *mxs_phy)
>  {
>  	return mxs_phy->data == &imx6ul_phy_data;
> @@ -305,12 +314,29 @@ static int mxs_phy_pll_enable(void __iomem *base, bool enable)
>  	return ret;
>  }
>
> +/*
> + * The imx8ulp phy registers are not properly reset after a warm
> + * reset (ERR051269). Using the following steps to reset DEBUG and
> + * PLL_SIC regs. CTRL and PWD regs are reset by "SFT" bit in
> + * stmp_reset_block().
> + */
> +static void mxs_phy_regs_reset(void __iomem *base)
> +{
> +	writel(0x7f180000, base + HW_USBPHY_DEBUG_SET);
> +	writel(~0x7f180000, base + HW_USBPHY_DEBUG_CLR);
> +	writel(0x00d12000, base + HW_USBPHY_PLL_SIC_SET);
> +	writel(~0x00d12000, base + HW_USBPHY_PLL_SIC_CLR);
> +}
> +
>  static int mxs_phy_hw_init(struct mxs_phy *mxs_phy)
>  {
>  	int ret;
>  	void __iomem *base = mxs_phy->phy.io_priv;
>
> -	if (is_imx7ulp_phy(mxs_phy)) {
> +	if (is_imx8ulp_phy(mxs_phy))
> +		mxs_phy_regs_reset(base);
> +
> +	if (is_imx7ulp_phy(mxs_phy) || is_imx8ulp_phy(mxs_phy)) {
>  		ret = mxs_phy_pll_enable(base, true);
>  		if (ret)
>  			return ret;
> @@ -368,7 +394,7 @@ static int mxs_phy_hw_init(struct mxs_phy *mxs_phy)
>  	return 0;
>
>  disable_pll:
> -	if (is_imx7ulp_phy(mxs_phy))
> +	if (is_imx7ulp_phy(mxs_phy) || is_imx8ulp_phy(mxs_phy))
>  		mxs_phy_pll_enable(base, false);
>  	return ret;
>  }
> @@ -487,7 +513,7 @@ static void mxs_phy_shutdown(struct usb_phy *phy)
>  	writel(BM_USBPHY_CTRL_CLKGATE,
>  	       phy->io_priv + HW_USBPHY_CTRL_SET);
>
> -	if (is_imx7ulp_phy(mxs_phy))
> +	if (is_imx7ulp_phy(mxs_phy) || is_imx8ulp_phy(mxs_phy))
>  		mxs_phy_pll_enable(phy->io_priv, false);
>
>  	if (mxs_phy->phy_3p0)
> --
> 2.34.1
>