Re: [RFC PATCH 1/1] usb: dwc3: Clear SUSPHY before issuing core soft reset

[Thinh Nguyen]

On Thu, Oct 01, 2026, Elson Serrao wrote:
> The controller clears DCTL.CSFTRST only after all required logic has
> been reset and all PHY clocks are active. If SUSPHY remains set, the PHY
> may not be fully active during the reset sequence, causing the core soft
> reset to fail to complete.
>  
> Clear SUSPHY before asserting DCTL.CSFTRST to ensure the PHY remains
> active while the reset is in progress.
> 
> Fixes: cc5bfc4e16fc ("usb: dwc3: Set SUSPENDENABLE soon after phy init")
> Signed-off-by: Elson Serrao <elson.serrao@xxxxxxxxxxxxxxxx>
> ---
>  drivers/usb/dwc3/core.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index fd5c2cd36c59..282a853c364e 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -332,6 +332,13 @@ int dwc3_core_soft_reset(struct dwc3 *dwc)
>  	if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_HOST)
>  		return 0;
>  
> +	/*
> +	 * The core clears DCTL.CSFTRST only after all necessary logic is
> +	 * reset and all PHY clocks are active/running. Clear SUSPHY before
> +	 * issuing the reset so that the PHY is active.
> +	 */
> +	dwc3_enable_susphy(dwc, false);
> +
>  	reg = dwc3_readl(dwc, DWC3_DCTL);
>  	reg |= DWC3_DCTL_CSFTRST;
>  	reg &= ~DWC3_DCTL_RUN_STOP;
> -- 
> 2.34.1
> 

Most platforms require SUSPHY to be set before soft reset. Can you
handle this via a pre_soft_reset() glue_ops for the affected platform
instead?

Thanks,
Thinh