Re: [PATCH] usb: dwc2: wa for isoc packet tx fifo flush at periodic frame boundary

[Thinh Nguyen]

On Wed, Oct 14, 2026, Fabrice Gasnier wrote:
> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> index 102169b40419..9f02075ba15b 100644
> --- a/drivers/usb/dwc2/gadget.c
> +++ b/drivers/usb/dwc2/gadget.c
> @@ -3449,6 +3449,19 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
>  	if (hsotg->params.ipg_isoc_en)
>  		dcfg |= DCFG_IPG_ISOC_SUPPORDED;
>  
> +	/*
> +	 * WA for Device Flushes Ongoing ISOC IN Packet at End-of-Periodic-Frame Boundary.
> +	 * Once passed the end of periodic frame, and the controller is transmitting an
> +	 * ISOC IN packet, the device fulshes the transmit FIFO. Tune periodic frame

s/fulshes/flushes/

> +	 * interval to 95% instead of 80% to avoid it.
> +	 */
> +	if (using_desc_dma(hsotg) &&
> +	    (hsotg->hw_params.snpsid >= DWC2_CORE_REV_2_70a &&
> +	     hsotg->hw_params.snpsid <= DWC2_CORE_REV_4_00a)) {

This also affects the HS and FS IOT cores 1.00a. Please add
DWC2_HS_IOT_REV_1_00a and DWC2_FS_IOT_REV_1_00a here.

> +		dcfg &= ~DCFG_PERFRINT_MASK;
> +		dcfg |= ((DCFG_PERFRINT_LIMIT << DCFG_PERFRINT_SHIFT) & DCFG_PERFRINT_MASK);

This can just be:
		dcfg |= DCFG_PERFRINT(DCFG_PERFRINT_LIMIT);

This conflicts with your "[PATH] dwc2: fix fifo reinit in
dwc2_hsotg_core_init_disconnected". Please send both as a series and add
Cc stable.

Thanks,
Thinh