Re: [PATCH v3 5/5] usb: dwc3-am62: add workaround for Errata i2409

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

On Wed, Feb 14, 2024, Roger Quadros wrote:
> All AM62 devices have Errata i2409 [1] due to which
> USB2 PHY may lock up due to short suspend.
> 
> Workaround involves setting bit 5 and 4 PLL_REG12
> in PHY2 register space after USB controller is brought
> out of LPSC reset but before controller initialization.
> 
> Handle this workaround.
> 
> [1] - https://urldefense.com/v3/__https://www.ti.com/lit/er/sprz487d/sprz487d.pdf__;!!A4F2R9G_pg!djrhB3gW9q9ZBzv7_15MDrMqxOeQuOMbrceRs6NsnAzMMrENAGLMrt-zvq5avRei9uC6r3x9kItwobKxn2Vw$ 
> 
> Signed-off-by: Roger Quadros <rogerq@kernel.org>
> ---
> Changelog:
> 
> v3:
> - move requesting of PHY2 region to right where we need it
> 
> v2:
> - don't add phy read/write helpers or add phy to private data
> 	https://urldefense.com/v3/__https://lore.kernel.org/all/20240205141221.56076-5-rogerq@kernel.org/__;!!A4F2R9G_pg!djrhB3gW9q9ZBzv7_15MDrMqxOeQuOMbrceRs6NsnAzMMrENAGLMrt-zvq5avRei9uC6r3x9kItwobI0OZD1$ 
> 
> v1: https://urldefense.com/v3/__https://lore.kernel.org/all/20240201121220.5523-5-rogerq@kernel.org/__;!!A4F2R9G_pg!djrhB3gW9q9ZBzv7_15MDrMqxOeQuOMbrceRs6NsnAzMMrENAGLMrt-zvq5avRei9uC6r3x9kItwofeJSsi1$ 
> ---
>  drivers/usb/dwc3/dwc3-am62.c | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-am62.c b/drivers/usb/dwc3/dwc3-am62.c
> index af1ce934e7fb..163278050595 100644
> --- a/drivers/usb/dwc3/dwc3-am62.c
> +++ b/drivers/usb/dwc3/dwc3-am62.c
> @@ -101,6 +101,11 @@
>  #define PHY_CORE_VOLTAGE_MASK	BIT(31)
>  #define PHY_PLL_REFCLK_MASK	GENMASK(3, 0)
>  
> +/* USB PHY2 register offsets */
> +#define	USB_PHY_PLL_REG12		0x130
> +#define	USB_PHY_PLL_LDO_REF_EN		BIT(5)
> +#define	USB_PHY_PLL_LDO_REF_EN_EN	BIT(4)
> +
>  #define DWC3_AM62_AUTOSUSPEND_DELAY	100
>  
>  struct dwc3_am62 {
> @@ -184,8 +189,9 @@ static int dwc3_ti_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct device_node *node = pdev->dev.of_node;
>  	struct dwc3_am62 *am62;
> -	int i, ret;
>  	unsigned long rate;
> +	void __iomem *phy;
> +	int i, ret;
>  	u32 reg;
>  
>  	am62 = devm_kzalloc(dev, sizeof(*am62), GFP_KERNEL);
> @@ -227,6 +233,17 @@ static int dwc3_ti_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	/* Workaround Errata i2409 */
> +	phy = devm_platform_ioremap_resource(pdev, 1);
> +	if (IS_ERR(phy)) {
> +		dev_err(dev, "can't map PHY IOMEM resource. Won't apply i2409 fix.\n");
> +		phy = NULL;
> +	} else {
> +		reg = readl(phy + USB_PHY_PLL_REG12);
> +		reg |= USB_PHY_PLL_LDO_REF_EN | USB_PHY_PLL_LDO_REF_EN_EN;
> +		writel(reg, phy + USB_PHY_PLL_REG12);
> +	}
> +
>  	/* VBUS divider select */
>  	am62->vbus_divider = device_property_read_bool(dev, "ti,vbus-divider");
>  	reg = dwc3_ti_readl(am62, USBSS_PHY_CONFIG);
> 
> -- 
> 2.34.1
> 

Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>

BR,
Thinh