Re: [PATCH] usb: dwc3: Use the correct PHY mode for USB3 PHY

[Thinh Nguyen]

Hi,

On Mon, Oct 12, 2026, Prashanth K wrote:
> DWC3 currently configures USB3 PHYs with PHY_MODE_USB_HOST when
> switching the controller to host mode. Even though usb_add_hcd()
> sets the flag corrrectly, it gets overwritten in DWC3 layer.
> 
> Some PHY drivers distinguish between USB2 and SS host modes and
> expect USB3 PHYs to be configured with PHY_MODE_USB_HOST_SS. Using
> PHY_MODE_USB_HOST may result in incorrect PHY programming. Fix this
> by using PHY_MODE_USB_HOST_SS for USB3 PHYs.
> 
> Signed-off-by: Prashanth K <prashanth.k@xxxxxxxxxxxxxxxx>
> ---
>  drivers/usb/dwc3/core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index fd5c2cd36c59..1bb87a370725 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -251,7 +251,7 @@ static void __dwc3_set_mode(struct work_struct *work)
>  			for (i = 0; i < dwc->num_usb2_ports; i++)
>  				phy_set_mode(dwc->usb2_generic_phy[i], PHY_MODE_USB_HOST);
>  			for (i = 0; i < dwc->num_usb3_ports; i++)
> -				phy_set_mode(dwc->usb3_generic_phy[i], PHY_MODE_USB_HOST);
> +				phy_set_mode(dwc->usb3_generic_phy[i], PHY_MODE_USB_HOST_SS);
>  
>  			if (dwc->dis_split_quirk) {
>  				reg = dwc3_readl(dwc, DWC3_GUCTL3);
> @@ -1643,7 +1643,7 @@ static int dwc3_core_init_mode(struct dwc3 *dwc)
>  		for (i = 0; i < dwc->num_usb2_ports; i++)
>  			phy_set_mode(dwc->usb2_generic_phy[i], PHY_MODE_USB_HOST);
>  		for (i = 0; i < dwc->num_usb3_ports; i++)
> -			phy_set_mode(dwc->usb3_generic_phy[i], PHY_MODE_USB_HOST);
> +			phy_set_mode(dwc->usb3_generic_phy[i], PHY_MODE_USB_HOST_SS);
>  
>  		ret = dwc3_host_init(dwc);
>  		if (ret)
> -- 
> 2.34.1
> 

Can you take a look at Sashiko's review comments? I think the points
raised there are valid and should be addressed:

https://lore.kernel.org/linux-usb/sashiko-outbox-167906@xxxxxxxxxx/

Thanks,
Thinh