Re: [PATCH] usb: dwc3: xilinx: set coherency mode for AMD versal adaptive platform

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

On Wed, Jun 04, 2025, Radhey Shyam Pandey wrote:
> If device is coherent or if DMA (direct memory access) is translated by
> an IOMMU then program USB2.0 IP to route transactions through the CCI for
> coherency even if the target of transaction is in low power domain (LPD).
> 
> Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
> ---
>  drivers/usb/dwc3/dwc3-xilinx.c | 34 ++++++++++++++++++++++------------
>  1 file changed, 22 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c
> index 4ca7f6240d07..00e613c4d8c0 100644
> --- a/drivers/usb/dwc3/dwc3-xilinx.c
> +++ b/drivers/usb/dwc3/dwc3-xilinx.c
> @@ -32,6 +32,9 @@
>  #define XLNX_USB_TRAFFIC_ROUTE_CONFIG		0x005C
>  #define XLNX_USB_TRAFFIC_ROUTE_FPD		0x1
>  
> +/* USB 2.0 IP Register */
> +#define XLNX_USB2_TRAFFIC_ROUTE_CONFIG		0x0044
> +
>  #define XLNX_USB_FPD_PIPE_CLK			0x7c
>  #define PIPE_CLK_DESELECT			1
>  #define PIPE_CLK_SELECT				0
> @@ -66,6 +69,23 @@ static void dwc3_xlnx_mask_phy_rst(struct dwc3_xlnx *priv_data, bool mask)
>  	writel(reg, priv_data->regs + XLNX_USB_PHY_RST_EN);
>  }
>  
> +static void dwc3_xlnx_set_coherency(struct dwc3_xlnx *priv_data, u32 coherency_offset)
> +{
> +	struct device		*dev = priv_data->dev;
> +	u32			reg;
> +
> +	/*
> +	 * This routes the USB DMA traffic to go through FPD path instead
> +	 * of reaching DDR directly. This traffic routing is needed to
> +	 * make SMMU and CCI work with USB DMA.
> +	 */
> +	if (of_dma_is_coherent(dev->of_node) || device_iommu_mapped(dev)) {
> +		reg = readl(priv_data->regs + coherency_offset);
> +		reg |= XLNX_USB_TRAFFIC_ROUTE_FPD;
> +		writel(reg, priv_data->regs + coherency_offset);
> +	}
> +}
> +
>  static int dwc3_xlnx_init_versal(struct dwc3_xlnx *priv_data)
>  {
>  	struct device		*dev = priv_data->dev;
> @@ -92,6 +112,7 @@ static int dwc3_xlnx_init_versal(struct dwc3_xlnx *priv_data)
>  	}
>  
>  	dwc3_xlnx_mask_phy_rst(priv_data, true);
> +	dwc3_xlnx_set_coherency(priv_data, XLNX_USB2_TRAFFIC_ROUTE_CONFIG);
>  
>  	return 0;
>  }
> @@ -102,7 +123,6 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
>  	struct reset_control	*crst, *hibrst, *apbrst;
>  	struct gpio_desc	*reset_gpio;
>  	int			ret = 0;
> -	u32			reg;
>  
>  	priv_data->usb3_phy = devm_phy_optional_get(dev, "usb3-phy");
>  	if (IS_ERR(priv_data->usb3_phy)) {
> @@ -219,17 +239,7 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
>  		usleep_range(5000, 10000);
>  	}
>  
> -	/*
> -	 * This routes the USB DMA traffic to go through FPD path instead
> -	 * of reaching DDR directly. This traffic routing is needed to
> -	 * make SMMU and CCI work with USB DMA.
> -	 */
> -	if (of_dma_is_coherent(dev->of_node) || device_iommu_mapped(dev)) {
> -		reg = readl(priv_data->regs + XLNX_USB_TRAFFIC_ROUTE_CONFIG);
> -		reg |= XLNX_USB_TRAFFIC_ROUTE_FPD;
> -		writel(reg, priv_data->regs + XLNX_USB_TRAFFIC_ROUTE_CONFIG);
> -	}
> -
> +	dwc3_xlnx_set_coherency(priv_data, XLNX_USB_TRAFFIC_ROUTE_CONFIG);
>  err:
>  	return ret;
>  }
> 
> base-commit: a0bea9e39035edc56a994630e6048c8a191a99d8
> -- 
> 2.34.1
> 

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

BR,
Thinh