Re: [PATCH] mach-snapdragon: of_fixup: support new flat dwc3 node

[Sumit Garg <sumit.garg@kernel.org>]

On Wed, Jan 14, 2026 at 02:57:32PM +0100, Casey Connolly wrote:
> Qualcomm DTs are being updated to use a new format where the dwc3 glue
> node and controller are combined into a single DT node. Update the fixup
> code to handle this case.
> 
> Signed-off-by: Casey Connolly <casey.connolly@linaro.org>
> ---
>  arch/arm/mach-snapdragon/of_fixup.c | 40 +++++++++++++++++++++--------
>  1 file changed, 29 insertions(+), 11 deletions(-)

Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>

-Sumit

> 
> diff --git a/arch/arm/mach-snapdragon/of_fixup.c b/arch/arm/mach-snapdragon/of_fixup.c
> index eec2c0c757e0..5b6076ea8e57 100644
> --- a/arch/arm/mach-snapdragon/of_fixup.c
> +++ b/arch/arm/mach-snapdragon/of_fixup.c
> @@ -31,31 +31,37 @@
>   * USB controllers. Rather than requiring source level DT changes, we fix up
>   * DT here. This improves compatibility with upstream DT and simplifies the
>   * porting process for new devices.
>   */
> -static int fixup_qcom_dwc3(struct device_node *root, struct device_node *glue_np)
> +static int fixup_qcom_dwc3(struct device_node *root, struct device_node *glue_np, bool flat)
>  {
>  	struct device_node *dwc3;
>  	int ret, len, hsphy_idx = 1;
>  	const __be32 *phandles;
>  	const char *second_phy_name;
>  
>  	debug("Fixing up %s\n", glue_np->name);
>  
> +	/* New DT flattens the glue and controller into a single node. */
> +	if (flat) {
> +		dwc3 = glue_np;
> +		debug("%s uses flat DT\n", glue_np->name);
> +	} else {
> +		/* Find the DWC3 node itself */
> +		dwc3 = of_find_compatible_node(glue_np, NULL, "snps,dwc3");
> +		if (!dwc3) {
> +			log_err("Failed to find dwc3 node\n");
> +			return -ENOENT;
> +		}
> +	}
> +
>  	/* Tell the glue driver to configure the wrapper for high-speed only operation */
>  	ret = of_write_prop(glue_np, "qcom,select-utmi-as-pipe-clk", 0, NULL);
>  	if (ret) {
>  		log_err("Failed to add property 'qcom,select-utmi-as-pipe-clk': %d\n", ret);
>  		return ret;
>  	}
>  
> -	/* Find the DWC3 node itself */
> -	dwc3 = of_find_compatible_node(glue_np, NULL, "snps,dwc3");
> -	if (!dwc3) {
> -		log_err("Failed to find dwc3 node\n");
> -		return -ENOENT;
> -	}
> -
>  	phandles = of_get_property(dwc3, "phys", &len);
>  	len /= sizeof(*phandles);
>  	if (len == 1) {
>  		log_debug("Only one phy, not a superspeed controller\n");
> @@ -103,15 +109,27 @@ static int fixup_qcom_dwc3(struct device_node *root, struct device_node *glue_np
>  }
>  
>  static void fixup_usb_nodes(struct device_node *root)
>  {
> -	struct device_node *glue_np = root;
> +	struct device_node *glue_np = root, *tmp;
>  	int ret;
> +	bool flat;
> +
> +	while (true) {
> +		flat = false;
> +		/* First check for the old DT format with glue node then the new flattened format */
> +		tmp = of_find_compatible_node(glue_np, NULL, "qcom,dwc3");
> +		if (!tmp) {
> +			tmp = of_find_compatible_node(glue_np, NULL, "qcom,snps-dwc3");
> +			flat = !!tmp;
> +		}
> +		if (!tmp)
> +			break;
> +		glue_np = tmp;
>  
> -	while ((glue_np = of_find_compatible_node(glue_np, NULL, "qcom,dwc3"))) {
>  		if (!of_device_is_available(glue_np))
>  			continue;
> -		ret = fixup_qcom_dwc3(root, glue_np);
> +		ret = fixup_qcom_dwc3(root, glue_np, flat);
>  		if (ret)
>  			log_warning("Failed to fixup node %s: %d\n", glue_np->name, ret);
>  	}
>  }
> -- 
> 2.51.0
>