Re: [PATCH v2 5/5] usb: dwc3-am62: add workaround for Errata i2409

Andrew Davis
2024-02-05T18:07:22Z

On 2/5/24 8:12 AM, 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://www.ti.com/lit/er/sprz487d/sprz487d.pdf
>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> Cc: Conor Dooley <conor+dt@kernel.org>
> Signed-off-by: Roger Quadros <rogerq@kernel.org>
> ---
>
> Notes:
> Changelog:
>
> v2:
> - don't add phy read/write helpers or add phy to private data
>
> v1: https://lore.kernel.org/all/20240201121220.5523-5-rogerq@kernel.org/
>
> drivers/usb/dwc3/dwc3-am62.c | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/dwc3-am62.c b/drivers/usb/dwc3/dwc3-am62.c
> index af1ce934e7fb..5ae5c3087b0f 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);
> @@ -201,6 +207,12 @@ static int dwc3_ti_probe(struct platform_device *pdev)
> return PTR_ERR(am62->usbss);
> }
>
> + 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;
> + }

Why not move this down to where you use it below, then just have
it be an if/else with the work around in the if (!IS_ERR(phy))
and the warning in the else.

Andrew

> +
> am62->usb2_refclk = devm_clk_get(dev, "ref");
> if (IS_ERR(am62->usb2_refclk)) {
> dev_err(dev, "can't get usb2_refclk\n");
> @@ -227,6 +239,13 @@ static int dwc3_ti_probe(struct platform_device *pdev)
> if (ret)
> return ret;
>
> + /* Workaround Errata i2409 */
> + if (phy) {
> + 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);